The Big Bang Theory

CBS (ended 2019)




Episode Guide

    • The Stockholm Syndrome
      Season 12 - Episode 24

      In the series finale, Howard and Bernadette leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; and Raj makes a new friend as the gang travels together into an uncharted future.

    • The Closure Alternative
      Season 6 - Episode 21

      Sheldon feels lost after one of his favorite TV shows gets canceled too soon and Amy tries to help him get over his compulsive need for closure. Meanwhile, Raj discovers a secret about his new love interest, Lucy.

    • The Monster Isolation
      Season 6 - Episode 17

      Sheldon has Penny as a guest on a "Fun with Flags" episode and she gets him to attend her acting class' presentation of "A Streetcar Named Desire". Raj drops out after Lucy unexpectedly leaves their first get together.

    • The Love Spell Potential
      Season 6 - Episode 23

      After an aborted girls' trip to Vegas, they are all playing Dungeons and Dragons together. Raj leaves after he finds that Lucy is free and he pushes her to do things that scare her. In the game, Penny casts a love spell on Sheldon and Amy's characters which gets Amy very upset because they are treating her and Sheldon's relationship as a joke.

    • The Scavenger Vortex
      Season 7 - Episode 3
      Raj plans a scavenger hunt for the group that tests their science skills as well as their life skills. This event brings out the both the good and bad in the competitors.
    • The Romance Resonance
      Season 7 - Episode 6
      Sheldon makes a scientific discovery, but it ends up making him feel like a cheater. When Howard romances Bernadette, Penny decides to try it with Leonard.
    • The Tangible Affection Proof
      Season 6 - Episode 16

      The couples are getting for Valentines' Day. Leonard, Penny, Howard and Bernadette are going to dinner. Sheldon and Amy are trying to get the perfect gifts for each other. Raj and Stuart are planning a singles only party at The Comic Book Store.

    • The Thanksgiving Decoupling
      Season 7 - Episode 9

      Thanksgiving plans include dinner at the Wolowitz home but Sheldon is less than pleased about the location. Penny’s past comes back to haunt her.

    • The Bon Voyage Reaction
      Season 6 - Episode 24

      Leonard gets a new job opportunity to work abroad for the summer and Sheldon is feeling a little bit jealous. Meanwhile, Raj tries to move his relationship with Lucy into a new direction by introducing her to his friends, but he fears that she may not like them.

    • 3/7/13

      Raj and Lucy have their first date meeting in a library and texting to each other. The guys have to promote science careers for women at Howard's old middle school, while the girls go to Disneyland and get made up as Disney Princesses.

    • The Change Constant
      Season 12 - Episode 23

      Sheldon, Amy and the gang eagerly await the announcement of the winner of the Nobel Prize in physics.

    • The Egg Salad Equivalency
      Season 6 - Episode 12

      Sheldon gets all the guys before the Human Resources Department when he tries to talk to Alex about her advances to Leonard. Alex's actions also make Penny feel insecure.

    • The Closet Reconfiguration
      Season 6 - Episode 19

      Bernadette prepares a dinner for the gang, however Sheldon brings his own Thai take-out food after she makes Sheldon's Thai food from scratch. Sheldon rearranges Howard and Bernadette's closet and finds an unopened letter from Howard's father, sent for his 18th birthday. Penny and Leonard decide to invite the gang for a formal dinner party.

    • The Bakersfield Expedition
      Season 6 - Episode 13

      The guys have a road trip in order to attend to a comic book convention, dressed as "Star Trek: The Next Generation". Stopping to take some photos in costume, Leonard's car is stolen. Meanwhile the girls are at home trying to figure out a comic book.

    • The Re-Entry Minimisation
      Season 6 - Episode 4
      Howard is offended when his return from space is met with little fanfare but he gets an even bigger surprise at home. Game Night turns into a battle royale between Penny and Sheldon.
    • The Launch Acceleration
      Season 5 - Episode 23
      Howard's space mission is moved up, conflicting with the wedding. Meanwhile, Leonard mentions something in the bedroom that freaks out Penny.
    • The Opening Night Excitation
      Season 9 - Episode 11

      Sheldon plans a huge birthday surprise for Amy while Leonard, Raj and Howard take Wil Wheaton with them to see the new Star Wars movie.

    • The Bow Tie Asymmetry
      Season 11 - Episode 24

      Sheldon and Amy's families fly in for their wedding, while Howard manages to convince Mark Hamill to perform the ceremony.

    • The Indecision Amalgamation
      Season 7 - Episode 19

      Raj wrestles with dating two women at the same time, Penny is offered a part in a trashy movie and Sheldon can't decide between two gaming systems.

    • The Hawking Excitation
      Season 5 - Episode 21

      When Stephen Hawking visits Caltech to give a lecture, Sheldon goes to great lengths for a chance to meet his hero in person.

    • The Proton Transmogrification
      Season 7 - Episode 22

      Professor Proton pays Sheldon a visit after Sheldon suffers a tragic loss. Meanwhile, Leonard can't help competing with Penny when they reach a milestone in their relationship, and Amy and Bernadette treat the guys by making them a Star Wars Day gift.

    • The Maternal Conclusion
      Season 12 - Episode 22

      Leonard is pleasantly surprised when his mother comes to visit and she's genuinely kind to him, until he finds out the real reason she's there. Also, Denise and Stuart overstay their welcome at the Wolowitz house.

    • The Raiders Minimization
      Season 7 - Episode 4
      Sheldon plots to get even with Amy after she wrecks Raiders of the Lost Ark. Leonard learns a new technique to influence Penny. Stuart and Raj turn to the Internet for dating help.
    • The Locomotion Manipulation
      Season 7 - Episode 15
      Sheldon and Amy go on a trip to wine country with Howard and Bernadette. Penny and Leonard rush Raj's dog to the vet.
    • The Proton Resurgence
      Season 6 - Episode 22

      When Sheldon and Leonard learn their favorite TV scientist is available to hire, they seek to do so. Howard and Bernadette are tasked with watching Raj's dog.

    • The Cooper-Kripke Inversion
      Season 6 - Episode 14

      Sheldon is forced to work with Kripke and while in competition with Kripke, ends up spreading rumors about his sexual relationship with Amy. Howard and Raj get action figures of themselves that cost $1000.

    • The Relationship Diremption
      Season 7 - Episode 20

      Raj and Howard double-date and the latter is flushed with embarrassment after Raj's girlfriend reveals a secret she knows about Howard. Meanwhile, Sheldon is at loose ends when he begins to believe he's wasted his life trying to prove string theory.

    • The Itchy Brain Simulation
      Season 7 - Episode 8
      Sheldon discovers a mistake that Leonard made years ago and forces him to walk a mile in his shoes. Lucy is confronted by Penny over her break up with Raj.
    • The Fish Guts Displacement
      Season 6 - Episode 10

      Howard and Bernadette have a tense dinner with both of her parents. The subject of Mr. Rostenkowski's weekend fishing trip comes up and Howard is hooked into going with him. The guys visit Penny to learn all about fishing since she used to go with her dad. Sheldon shows up at Amy's apartment to find his girlfriend sick. After initially rejecting her request, Sheldon stays to take care of Amy the way his mother took care of him, sometimes a bit intimately.

    • The Santa Simulation
      Season 6 - Episode 11

      The guys plan to play Dungeons and Dragons without inviting the girls, which causes arguments among them and the girls. After playing for some time, the girls show up dressed sexily for a girls' night out and Raj goes with them to the nightclub.

    • The Spoiler Alert Segmentation
      Season 6 - Episode 15

      With Leonard mad at Sheldon, he moves in with Penny. Amy notes that she would be the perfect roommate for Sheldon since she knows him so well and he wouldn't have to break in someone else. Sheldon and Penny are not happy with these arrangements. Raj is trapped in the Wolowitz house with Howard's lonely mother.

    • The Hofstadter Insufficiency
      Season 7 - Episode 1
      Sheldon and Penny share intimate secrets while Leonard is away at sea. Bernadette and Amy have a girls' night out without Penny. Howard takes Raj to a university event so he can utilize his new found ability of talking to women.
    • The Big Bran Hypothesis
      Season 1 - Episode 2
      Leonard volunteers to sign for a package in an attempt to make a good impression on Penny, but when he enlists Sheldon for help, his attempt at chivalry goes terribly awry.
    • The Proton Displacement
      Season 7 - Episode 7

      When Professor Proton seeks advice from Leonard, Sheldon is hurt and contacts Bill Nye. Howard interrupts Raj’s girls night out.

    • The Grasshopper Experiment
      Season 1 - Episode 8

      Raj's parents set him up on a blind date, and when he discovers he can talk to her, she shows interest in Sheldon.

    • The Middle Earth Paradigm
      Season 1 - Episode 6

      Penny hosts a Halloween party, putting Leonard, Sheldon, Howard, and Raj through a new test of their social skills.

    • The Habitation Configuration
      Season 6 - Episode 7
      Howard prepares to finally move out of his mother's house and in with Bernadette but it proves to be kind of difficult. Amy gets mad at Sheldon for taking Wil Wheaton's side and not hers, so he turns to Penny for advice.
    • The Status Quo Combustion
      Season 7 - Episode 24

      In the Season 7 finale, Sheldon gets caught up in all the life-altering changes going on around him and considers a monumental move.

    • The Dumpling Paradox
      Season 1 - Episode 7

      With Howard AWOL with one of her friends, Penny is recruited to fill in for him on the guys' Halo team.

    • The Earworm Reverberation
      Season 9 - Episode 10

      Sheldon goes crazy trying to figure out the name of the song he can't get out of his head, much to the annoyance of Leonard and Penny. Meanwhile, Raj and Howard create a fan page for their band.

    • The Brain Bowl Incubation
      Season 10 - Episode 8

      A successful gene experimentation leaves Sheldon excited to procreate with Amy, and he pulls out all stops to get her on board. Meanwhile, Raj is reluctant to reveal what the new woman in his life does for a living.

    • The Cooper Extraction
      Season 7 - Episode 11
      Sheldon leaves to be with his sister for her first child's birth. In his absence, the gang wonders what their lives would have been like had he not been part of the group.
    • The Higgs Boson Observation
      Season 6 - Episode 3

      Sheldon hires an assistant. Amy gets incredibly jealous of Sheldon having a female assistant, but Alex is actually more interested in Leonard. Meanwhile, Howard's return from space has been delayed a week and he starts to lose his mind because of it.

    • The Tenure Turbulence
      Season 6 - Episode 20

      Competition between the guys increases when a slot for a tenured professor opens up and they start to schmooze the tenure committee members that include Mrs. Davies from Human Resources who Sheldon has crossed paths with before.

    • The Maternal Capacitance
      Season 2 - Episode 15
      A visit from Leonard's mother ends up bringing him and Penny closer.
    • The Cohabitation Experimentation
      Season 10 - Episode 4

      While her apartment is being fixed due to a flood, Amy decides to move in with Sheldon, who sees this as a scientific experiment. Meanwhile, Howard and Bernadette find out that Raj knows what sex their baby is and they wonder whether or not they want to know.

    • The Good Guy Fluctuation
      Season 5 - Episode 7

      Leonard finds himself drawn towards a comely comic book illustrator. Meanwhile, Sheldon tries to scare the gang for Halloween.

    • The Countdown Reflection
      Season 5 - Episode 24

      As Howard awaits blast-off, he recounts how the gang threw together a last-minute wedding for him and Bernadette.

    • The Holographic Excitation
      Season 6 - Episode 5
      The gang celebrates Halloween at Stuart's comic book store. Meanwhile, Leonard seduces Penny with science.
    • The Euclid Alternative
      Season 2 - Episode 5
      An intervention is used to try to force Sheldon to overcome his fear of driving.
    • The Long Distance Dissonance
      Season 10 - Episode 24

      On the Season 10 finale, Sheldon's former admirer, Dr. Ramona Nowitzki, turns up while Amy is visiting Princeton, and the gang is extremely concerned.

    • The Tangerine Factor
      Season 1 - Episode 17

      Penny's break-up spurs Leonard to summon the courage to ask her out, and each goes to Sheldon for advice on their upcoming date.

    • The Deception Verification
      Season 7 - Episode 2
      When Leonard returns from the North Sea, he and Sheldon go through an adjustment period. Howard has an unusual emotional reaction as a result of his relationship with his mother.
    • 3/17/08

      When they're invited to present at a physics conference, Sheldon's reluctance to share the credit leads to a tiff between him and Leonard, and Penny's intervention only exacerbates the situation.

    • The Jerusalem Duality
      Season 1 - Episode 12

      With Sheldon rattled and impossible to be around after meeting Dennis, a 15-year-old physicist who's smarter than he, the rest of the guys search for a way to eliminate the threat.

    • The Loobenfeld Decay
      Season 1 - Episode 10

      Leonard and Sheldon each lie to avoid hearing Penny sing in a production of Rent. However, Sheldon's lie becomes a bit too complicated for its own good.

    • The Zazzy Substitution
      Season 4 - Episode 3
      When Sheldon "breaks up" with Amy, the guys worry when he starts replacing her with cats.
    • The Toast Derivation
      Season 4 - Episode 17
      Told Leonard is the center of the gang and miffed that they've started hanging out at Raj's, Sheldon seeks to form a new group of friends of which he can be the center.
    • The Intimacy Acceleration
      Season 8 - Episode 16

      As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Also, Leonard, Amy, Raj and Emily spend the evening trying to escape a room with a "zombie." And, after returning from Mrs. Wolowitz' funeral, Bernadette and Howard run into trouble at the airport.

    • The Comic Book Store Regeneration
      Season 8 - Episode 15

      Amid the excitement of Stuart reopening his comic-book store, Howard gets some unsettling news; and after teaching Sheldon how to "let it go," Penny doesn't practice what she preaches when she learns something maddening about Amy. Meanwhile, Raj and Leonard run into a restaurant customer who looks a lot like actor Nathan Fillion.

    • The Peanut Reaction
      Season 1 - Episode 16
      Penny wants to throw a surprise party for Leonard, but Sheldon's indulgence at an electronics store throws her off-track.
    • The Gorilla Dissolution
      Season 7 - Episode 23

      A trying day at the movie shoot leaves Penny with questions about her life choices, so she decides to act on it; and caring for a bedridden Mrs. Wolowitz proves a challenge for Howard and Bernadette. Meanwhile, Sheldon offers relationship advice to Raj after he sees Emily at the movies with another man.

    • The Matrimonial Metric
      Season 11 - Episode 12

      To discover who would be most qualified to be best man and maid of honor at their wedding, Sheldon and Amy subject their friends to a series of secret experiments. Also, Penny reveals her true feelings about Amy.

    • The Barbarian Sublimation
      Season 2 - Episode 3
      Penny becomes addicted to an online game based on the world of Conan the Barbarian and persistantly pesters Sheldon for advice.
    • The Pancake Batter Anomaly
      Season 1 - Episode 11
      With his friends knowing how sour he acts when sick, and avoiding him as a result, Sheldon is nursed for by Penny, who hasn't a clue what she's in for.
    • The Stag Convergence
      Season 5 - Episode 22

      A bachelor party and his sexual past puts Howard's marriage to Bernadette in jeopardy.

    • The Nerdvana Annihilation
      Season 1 - Episode 14
      When the delivery of a full-size prop of 1960's The Time Machine makes Penny miss work, she scolds Leonard about his sci-fi collectibles. He decides it's time to give up such childish pursuits.
    • The Cooper-Nowitzki Theorem
      Season 2 - Episode 6

      The gang is mystified when a young undergraduate student is attracted to Sheldon.

    • The 43 Peculiarity
      Season 6 - Episode 8

      Raj and Howard try to figure out Sheldon's secret daily afternoon routine. Meanwhile, jealousy takes over Leonard and Penny's relationship.

    • The Bat Jar Conjecture
      Season 1 - Episode 13

      Sheldon finds himself booted from the gang's Physics Bowl team and replaced with Leslie, so he forms his own team, hoping to prove he's superior.

    • The Zarnecki Incursion
      Season 4 - Episode 19
      When Sheldon has his World of Warcraft account hacked and his character stolen from, the guys team up to discover out who did it. Meanwhile, Bernadette and Amy try to help Penny deal with Leonard's continuing relationship with Priya.
    • The Bitcoin Entanglement
      Season 11 - Episode 9

      Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment. Also, a seven-year-old video reveals a secret about Leonard and Penny's relationship.

    • The Panty Piñata Polarization
      Season 2 - Episode 7
      When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate. Howard and Raj search for the America's Next Top Model house.
    • The Pork Chop Indeterminacy
      Season 1 - Episode 15
      The rest of the gang fall for Sheldon's twin sister, and Leonard's plan to win her heart is derailed when Sheldon declares he'll be the one to decide who can date her.
    • The Thespian Catalyst
      Season 4 - Episode 14
      Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about Bernadette.
    • The Veracity Elasticity
      Season 10 - Episode 7

      Sheldon finds out that the repairs to Amy's apartment have been completed for weeks, while Leonard discovers that Penny has been removing his collectibles from the apartment.

    • The Luminous Fish Effect
      Season 1 - Episode 4

      Sheldon's getting fired forces him to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk.

    • The Bad Fish Paradigm
      Season 2 - Episode 1
      Penny opens up to a reluctant Sheldon after a less-than-stellar first date with Leonard, placing him in the uncomfortable position of having to keep a secret.
    • The Financial Permeability
      Season 2 - Episode 14
      When Sheldon loans money to Penny so she can pay her rent, it leads to Leonard coming face-to-face with her ex, Kurt.
    • The Monopolar Expedition
      Season 2 - Episode 23
      The guys' prestigious offer to work over the summer at the North Pole—and Penny's resultant behavior—leaves Leonard unsure if he should go.
    • The Flaming Spittoon Acquisition
      Season 5 - Episode 10

      Sheldon finds himself jealous when Amy goes on a date with Stuart. The other guys can't resist the allure of the latest collectable card game expansion pack.

    • The Decoupling Fluctuation
      Season 6 - Episode 2

      Sheldon once again has to keep a secret when he learns Leonard and Penny are going to break up. Howard keeps getting teased by his fellow astronauts in space.

    • The Discovery Dissipation
      Season 7 - Episode 10

      Sheldon goes through a hard time because of the attention of his newly discovered element. Also, Raj stays over at Howard's house creating some marriage tension between Howard and Bernadette.

    • The Recombination Hypothesis
      Season 5 - Episode 13

      Leonard asks Penny out on an impromptu romantic date.

    • The Date Night Variable
      Season 6 - Episode 1

      Howard is caught in an argument between Bernadette and his mom, even while he's in space. Meanwhile, with his friends on dates, Raj feels lonely.

    • The Geology Methodology
      Season 11 - Episode 7

      Bert asks Sheldon to collaborate with him on a geology project, but Sheldon is concerned about his reputation. Raj dates Bernadette's coworker.

    • The Fuzzy Boots Corollary
      Season 1 - Episode 3
      Leonard asks a woman out after he finds out that Penny is seeing someone.
    • The Prom Equivalency
      Season 8 - Episode 8

      Amy and Bernadette organize a prom to be held atop the guys' apartment complex, but Sheldon is leery of all the prom pomp, circumstance and romancing that goes with it.

    • The Friendship Turbulence
      Season 7 - Episode 17

      Bernadette tries to decrease the amount of friction in Howard and Sheldon's friendship. Penny's car breaks down and she is afraid she will have to return to The Cheesecake Factory.

    • The Hamburger Postulate
      Season 1 - Episode 5
      Fearing he's wasting his time on Penny, Leonard ends up making a connection with Leslie. Meanwhile, Sheldon frets over a change to his hamburger routine.
    • The Wiggly Finger Catalyst
      Season 5 - Episode 4

      Penny finds the perfect girl for Raj to date. Meanwhile, Sheldon uses Dungeons & Dragons dice to make life's trivial decisions.

    • The Comet Polarization
      Season 11 - Episode 21

      Sheldon's comic book store experiences changes when writer Neil Gaiman puts Stuart's store on the map. Also, Koothrappali takes credit for Penny's astronomical discovery, and friendships are threatened.

    • The Infestation Hypothesis
      Season 5 - Episode 2

      Sheldon is aghast to learn the new chair in Penny's apartment was someone else's garbage. Leonard and Priya try a long-distance relationship.

    • The Solo Oscillation
      Season 11 - Episode 13

      When Sheldon kicks Amy out to work solo, she and Leonard bond during a series of science experiments. Also, Bert the geologist replaces Howard in the band Footprints on the Moon, and Sheldon finds Penny a surprising source of scientific inspiration.

    • The Plagiarism Schism
      Season 12 - Episode 21

      Kripke has proof that Dr. Pemberton plagiarized his thesis in college, and Sheldon and Amy aren't sure if they should turn him in. Also, Howard is happily surprised to learn that Bernadette wasn't the only waitress at the Cheesecake Factory who had a crush on him back in the day.

    • The Staircase Implementation
      Season 3 - Episode 22
      A squabble over the thermostat setting leads to Leonard going over to Penny's and recounting for her the story of how he met and moved in with Sheldon.
    • The Roommate Transmogrification
      Season 4 - Episode 24
      Hearing Star Trek sex games between Leonard and Priya sends Raj to live with Sheldon. Bernadette's earning her Ph.D makes the guys mock Wolowitz for not having one even more.
    • The Transporter Malfunction
      Season 5 - Episode 20

      Sheldon faces a crisis of conscience after breaking a Star Trek toy given to him by Penny. Meanwhile, a lonesome Raj is smitten after a date set up by his parents.

    • The Vegas Renormalization
      Season 2 - Episode 21
      Leonard and Raj take Wolowitz to Las Vegas to help him get over his break-up with Leslie. Sheldon, home alone and looking forward to it, locks himself out and has only one other place to stay—Penny's.
    • The Prestidigitation Approximation
      Season 4 - Episode 18
      Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Priya disapproves of Leonard continuing to be friends with Penny.
    • The Bath Item Gift Hypothesis
      Season 2 - Episode 11

      Sheldon irks the gang over his obsession with proper Christmas gift protocol. Leonard is crushed when Penny dates a colleague of his.

    • The Griffin Equivalency
      Season 2 - Episode 4
      Full of confidence following being named one of People's "30 to Watch Under 30", Raj hits on Penny and becomes impossibly arrogant.
    • The Table Polarization
      Season 7 - Episode 16

      Leonard buys a dining room table which causes Sheldon to reevaluate the changes in his life. Meanwhile, Howard is offered a chance to go back to space and Bernadette struggles with whether or not to encourage him.

    • The Justice League Recombination
      Season 4 - Episode 11
      The guys get Zack and Penny to join their Justice League costume for a New Year's Eve bash at the comic book store.
    • The Cohabitation Formulation
      Season 4 - Episode 16
      Bernadette tells Howard that it's time to choose between moving in with her or staying with his mother. Leonard discovers Raj's sister Priya is back in town and reconnects with her, and Amy tries to comfort Penny when she finds out.
    • The Ornithophobia Diffusion
      Season 5 - Episode 9
      Sheldon tries to cure his phobia of birds, while Leonard and Penny go to a movie just as friends.
    • The Convention Conundrum
      Season 7 - Episode 14
      After failing to get tickets to Comic-Con, Sheldon decides to create his own convention and tries to get James Earl Jones to be a guest at it only to wind up spending the entire night with him. Meanwhile, the girls start to wonder if it is fun being an adult after going to a tea room that was filled little girls and their mothers.moreless
    • The D & D Vortex
      Season 12 - Episode 16

      The gang finds out Wil Wheaton hosts a celebrity Dungeons and Dragons game involving William Shatner, Joe Manganiello, Kareem Abdul-Jabbar and Kevin Smith. Deception and betrayal are the path to make it to the one open seat.

    • The Mommy Observation
      Season 7 - Episode 18

      While Sheldon and Howard continue their bonding holiday to Houston, Texas, Sheldon's surprise visit to see his Mommy forces him to start addressing a new reality. Meanwhile the rest of the gang are subjected to a Raj's surprise "Murder Mystery" party that leads the gang to speculate where they might all be 20 years from now.

    • The White Asparagus Triangulation
      Season 2 - Episode 9
      Sheldon is overexuberant that Leonard finally has a girlfriend matching his high standards.
    • The Weekend Vortex
      Season 5 - Episode 19

      Sheldon incurs Amy's ire when he chooses a weekend of videogaming with the guys over a birthday party for her aunt.

    • The Workplace Proximity
      Season 7 - Episode 5

      When Amy takes a job at the same University as Sheldon, it causes Sheldon to reevaluate the time he spends with her. Howard has a fight with Bernadette and finds himself sleeping on Raj's couch.

    • The Misinterpretation Agitation
      Season 8 - Episode 7

      Penny's flirtatious sales pitch is misunderstood by a doctor-client, while Bernadette and Amy debate whether female scientists ought to play the sexuality card.

    • The Anything Can Happen Recurrence
      Season 7 - Episode 21

      Problems arise between Amy, Penny and Bernadette because Sheldon tried something new and spontaneous. Howard provides assistance to Raj regarding his date Emily.

    • 10/19/09

      Sheldon looks forward to squaring off against the the one actor from the Star Trek universe he holds enmity towards—Wil Wheaton—in a fantasy collectable card game tournament. Howard cashes in on an old pact with Leonard to get Penny to set him up with a friend of hers.

    • The Confidence Erosion
      Season 11 - Episode 10

      Sheldon and Amy try to eliminate stress from planning their wedding by applying math to the process, and they end up at city hall. Also, Raj "breaks up" with Howard after realizing his best friend is undermining his self-confidence.

    • Pilot
      Season 1 - Episode 1

      Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins showing them that as much as they know about science, they know little about actual living.

    • The Codpiece Topology
      Season 2 - Episode 2
      Seeing Penny with another guy sends Leonard back to Leslie Winkle, much to Sheldon's dismay.
    • The Agreement Dissection
      Season 4 - Episode 21
      Miffed over Priya breaking down the Roommate Agreement using legal theory, Sheldon joins Penny, Bernadette, and Amy on their girls' night.
    • The Expedition Approximation
      Season 8 - Episode 6

      Sheldon and Raj undertake an underground research expedition that turns into a test of how long before they get under each other's skin. Meanwhile, Leonard and Penny argue about money, and go to Howard and Bernadette for advice.

    • The Proton Regeneration
      Season 11 - Episode 6

      Sheldon goes head-to-head with Wil Wheaton for the role of the new Professor Proton. Meanwhile, Penny steps in and takes care of Halley when Bernadette and Howard both wind up on bed rest.

    • The Isolation Permutation
      Season 5 - Episode 8

      When it is revealed that Penny and Bernadette went wedding dress shopping without her, Amy becomes heartbroken and pressures Sheldon for sex.

    • The Russian Rocket Reaction
      Season 5 - Episode 5

      Sheldon is miffed that Leonard plans to attend a party hosted by his nemesis, Wil Wheaton. Meanwhile, Howard is offered a chance to be a payload specialist on the International Space Station.

    • The Tesla Recoil
      Season 11 - Episode 8

      Leonard and Howard are furious after they learn Sheldon went to work with the military behind their backs. Also, while Bernadette is on bed rest, she asks Raj to do some digging when she suspects Ruchi is trying to steal her job.

    • The Sibling Realignment
      Season 11 - Episode 23

      When Sheldon learns that his mother won't attend his wedding unless he invites his brother, Georgie, he and Leonard travel to Texas to end a family feud. Also, the Wolowitz kids inadvertently infect Amy, Bernadette, Howard and Raj with pink eye.

    • The Adhesive Duck Deficiency
      Season 3 - Episode 8
      With the rest of the gang off on a desert camping trip to view the Leonid meteor shower, Sheldon must play hero after Penny slips in the tub and dislocates her shoulder.
    • The Celebration Reverberation
      Season 11 - Episode 11

      Sheldon and Howard plan birthday celebrations for Amy and Halley, respectively. Also, Leonard receives a Christmas letter from his brother that causes him to spiral out about his own lack of accomplishments.

    • The Robotic Manipulation
      Season 4 - Episode 1
      Howard uses a robotic arm for his own pleasure. Penny assists Sheldon with his first date.
    • The Occupation Recalibration
      Season 7 - Episode 13
      Sheldon is ordered to take some time off and finds relaxing challenging. Leonard continues to support Penny as she reevaluates her future. Stuart and Bernadette work together to replace a comic book for Howard.
    • The Geology Elevation
      Season 10 - Episode 9

      A geologist coworker's MacArthur Genius fellowship award leaves Sheldon stone cold jealous. Meanwhile, Howard stumbles upon a remote-control Stephen Hawking action figure that he invented. Hawking appears as himself.

    • 9/21/09
      Discovering that Leonard, Raj, and Howard fudged the results of his Arctic research expedition, a disgraced Sheldon heads home to Texas.
    • The Troll Manifestation
      Season 8 - Episode 14

      An online troll rips Leonard and Sheldon's published physics paper, so the guys rally to defend the two and expose the bully, while a girls night out leads to Penny, Amy and Bernadette dishing about embarrassing past events.

    • The Skank Reflex Analysis
      Season 5 - Episode 1

      After spending the night with Raj, Penny is worried that her friendship with the guys is in jeopardy, while Sheldon becomes the paintball team leader.

    • The Dependence Transcendence
      Season 10 - Episode 3

      While trying to meet the Air Force deadline, Sheldon tries an energy drink for the first time and starts to believe he has become an addict. Meanwhile, Amy takes Penny to a party thrown by one of her colleagues and Bernadette thinks something is wrong with her as she's not as excited for her new baby as everyone else is.

    • The Decision Reverberation
      Season 12 - Episode 20

      When Leonard's friends encourage him to stand up for what he wants instead of going along with the gang, he goes to President Siebert's office demanding that he be made principal investigator on a plasma physics study. Meanwhile, Raj is worried people won't take him seriously in his own field after publishing a paper that suggests the possibility of alien life.

    • The Gates Excitation
      Season 11 - Episode 18

      Penny gets the opportunity to host Bill Gates at work when his company wants to partner with her pharmaceutical company. Also, Leonard, Howard and Raj do everything in their power to meet him, while Sheldon thinks he is the victim of an April Fools prank.

    • The Neonatal Nomenclature
      Season 11 - Episode 16

      When Bernadette won't go into labor, all her friends try different tactics to get things started. Also, Howard confronts Bernadette after Amy accidentally reveals she's already chosen their son's name.

    • The Novelization Correlation
      Season 11 - Episode 15

      Leonard's novel causes differences of opinion about who the characters are based on. Also, Amy guest stars on the Wil Wheaton's new Professor Proton show.

    • The Maternal Congruence
      Season 3 - Episode 11
      A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.
    • The Locomotion Reverberation
      Season 10 - Episode 15

      When Sheldon hinders progress on the guidance-system project, Leonard comes up with a plan to get rid of him by giving him tickets to a historic railroad. Meanwhile, Penny and Amy take new-mommy Bernadette on a girls' night out, leaving baby Halley in the hands of Raj and Stuart.

    • The Bachelor Party Corrosion
      Season 9 - Episode 3

      The guys get together to throw Leonard a bachelor party in Mexico only to have car trouble put a damper on their plans. Meanwhile, Bernadette and Amy urge Penny to tell her parents that she is married.

    • The Mystery Date Observation
      Season 9 - Episode 8

      When Leonard, Penny and Bernadette learn that Amy is going out on a dinner date, the trio set out to spy on her and the guy. Meanwhile, Sheldon recruits Raj and Howard to find a woman for him, since they were responsible for getting Amy and he together.

    • The Emotion Detection Automation
      Season 10 - Episode 14

      Sheldon is intrigued with the of beta testing an MIT designed machine that purports to help read people’s emotions. Leonard tries to hide his anger when Penny announces that her brother is coming to town and staying with them and Raj invites his ex-girlfriends to give him dating advice.

    • The Escape Hatch Identification
      Season 10 - Episode 18

      When Raj moves out of his apartment to save money, both Howard and Bernadette and Leonard and Penny offer him a place to stay. Meanwhile, Sheldon calls Leonard's mother for relationship advice.

    • The Comic-Con Conundrum
      Season 10 - Episode 17

      When Raj no longer receives money from his father, he asks Sheldon to help him manage his finances.  Meanwhile, Penny insists on joining Leonard at Comic-Con and Bernadette finally figures out a way to get Howard to do some of the housework.

    • The Collaboration Contamination
      The Collaboration Contamination
      Season 11 - Episode 5


    • The Einstein Approximation
      Season 3 - Episode 14
      Stuck on the solution to a physics problem, Sheldon seeks a number of alternative approaches to change his thinking and free the mental block—including working with Penny at The Cheesecake Factory.
    • The Lizard-Spock Expansion
      Season 2 - Episode 8
      Sheldon wants to use an alternate version of rock-paper-scissors to help resolve conflicts. A girl Wolowitz has a major crush on falls for Leonard.
    • The Plimpton Stimulation
      Season 3 - Episode 21
      Sheldon hosts a visiting female physicist, but her intelligence seems matched by her libido.
    • The Beta Test Initiation
      Season 5 - Episode 14

      Leonard and Penny create lists of 'bugs' in their relationship in an attempt to strengthen it. Meanwhile, Sheldon and Amy create a YouTube video series called Fun with Flags, and Raj develops an unhealthy attachment to Siri on his iPhone.

    • The Gothowitz Deviation
      Season 3 - Episode 3
      Howard takes Raj along to check out the Goth dating scene. Sheldon uses chocolate as part of a behavior modification experiment on Penny.
    • The Pants Alternative
      Season 3 - Episode 18

      Sheldon's fear of speaking in front of large groups threatens his ability to accept an award, so the gang tries to help him get ready for the big night.

    • The Junior Professor Solution
      Season 8 - Episode 2

      Sheldon is ordered to teach a class, and the gang is surprised when Howard signs up to take it; and tensions between Penny and Bernadette afford Amy an opportunity to play one against the other.

    • The Military Miniaturization
      Season 10 - Episode 2

      The guys heads are in a spin when an Air Force bigwig approaches them about their revolutionary gyroscope invention; and Bernadette is upset with Penny after she accidentally leaks a secret to Bernadette's coworkers about her being pregnant.

    • The Explosion Implosion
      Season 11 - Episode 4

      Leonard is upset with the developing relationship between Penny and his mother; Sheldon and Howard bond over Howard's model rockets.

    • The Rhinitis Revelation
      Season 5 - Episode 6

      When his mother comes for another visit, Sheldon is disappointed that she's stopped being the mother he wants her to be.

    • The Spock Resonance
      Season 9 - Episode 7

      Before he's about to be interviewed for a documentary created by Leonard Nimoy's son, Sheldon reveals to Leonard and Penny that he was going to propose to Amy before she broke up with him and they try to convince him to admit that he's hurt. Meanwhile, Bernadette plans on renovating the house and Howard is not too happy about it.

    • The Convergence Convergence
      Season 9 - Episode 24

      Tensions arise when both of Leonard's parents and Sheldon's mother arrive to attend Leonard and Penny's second wedding ceremony, as they were not at the first one is Las Vegas.

    • The Wildebeest Implementation
      Season 4 - Episode 22
      Amy recognizes a dinner invitation to be a chance for Bernadette to spy on Leonard and Priya for Penny. Meanwhile, a lonely Raj considers taking experimental medication to cure himself of his inability to talk to women while sober, and Sheldon devises three-person chess.
    • The Septum Deviation
      Season 8 - Episode 9

      Leonard needs surgery for a deviated septum, and Sheldon gets his nose out of joint because he feels an operation is too dangerous and that his roommate may not make it out alive. Meanwhile, a distraught Raj learns his parents have divorced on the eve of their 40th anniversary.

    • The Reclusive Potential
      Season 11 - Episode 20

      Sheldon, Leonard, Howard and Raj go to a secluded cabin to meet a reclusive scientist while Penny and Bernadette throw Amy a bachelorette party.

    • The Terminator Decoupling
      Season 2 - Episode 17
      The gang is thrilled when they see Terminator: The Sarah Connor Chronicles' Summer Glau is also aboard their train to San Francisco for a scientific symposium. Meanwhile, Sheldon frets over having forgotten a paper he wants to present to George Smoot.
    • The Work Song Nanocluster
      Season 2 - Episode 18

      Penny's business selling hair accessories out of her apartment gets out of hand when an over-caffeinated Sheldon takes charge.

    • The Dead Hooker Juxtaposition
      Season 2 - Episode 19
      Penny feels threatened when another sexy woman moves into the apartment building and angered when she senses the guys are being taken advantage of.
    • The Werewolf Transformation
      Season 5 - Episode 18

      Sheldon is forced into altering his precious schedule after his barber falls ill. Meanwhile, the training required to be an astronaut has Wolowitz wondering if he has the right stuff.

    • The Perspiration Implementation
      Season 9 - Episode 5

      The guys want to learn to be better at sports so Barry Kripke teaches them fencing. Meanwhile the girls help Stuart try to get more women to come to the comic book store. Amy gets asked out by Stuart and Kripke but she turns them both down.

    • The Conjugal Conjecture
      Season 10 - Episode 1

      As the chaotic possibility of a looming romantic relationship between Lenard's father and Sheldon's mother causes strife amongst the families, Howard's paranoia grows as he contemplates the desires of the U. S. Air Force towards him and his invention.

    • The Inspiration Deprivation
      Season 12 - Episode 19

      After Amy has a meltdown from the pressure associated with winning a Nobel Prize, she is ordered by the University to lie low. Also, Howard and Raj try to relive the good old days after Howard buys a scooter that looks like the one he had years ago.

    • The Pirate Solution
      Season 3 - Episode 4
      Facing a return to India, Raj needs a job desperately enough to consider working for Sheldon. Meanwhile, Howard becomes a third wheel to Leonard and Penny.
    • 9/30/10
      Sheldon calculates that he'll be dead before technology exists to download his consciousness into a robot, so he goes on a binge of healthy living and ultra-safety.
    • The Shiny Trinket Maneuver
      Season 5 - Episode 12

      Sheldon finds himself in hot water when he doesn't appreciate Amy's recent accomplishment. Howard discovers Bernadette doesn't interact well with children.

    • The Parking Spot Escalation
      Season 6 - Episode 9

      When the University reassigns Sheldon's parking spot to Wolowitz, their fight affects the whole gang.

    • The Monetary Insufficiency
      Season 11 - Episode 22

      Sheldon goes to Vegas to win money for science. Also, Penny and Bernadette take Amy wedding dress shopping, but her terrible choice entangles them in a web of lies.

    • The Cushion Saturation
      Season 2 - Episode 16
      Paintball leads to a squabble between Sheldon and Penny, as well as romance between Howard and Leslie.
    • The Gorilla Experiment
      Season 3 - Episode 10

      Penny seeks Sheldon's help to better comprehend Leonard's physics work. Howard sees green when Leonard invites Bernadette to watch an experiment.

    • The Maternal Combustion
      Season 8 - Episode 23

      Personalities collide when Sheldon and Leonard's mothers finally meet. Meanwhile, Howard finally decides to "man up" and do his fair share of the housework - but not without a little help from his friends.

    • The Holiday Summation
      Season 10 - Episode 12

      The gang talks about what they did over the holidays. Sheldon and Amy go to visit Sheldon's mom, who is thrilled that they are living together, which confuses Sheldon. Leonard and Penny go through a hard time getting their Christmas tree and Howard and Bernadette have a hard time getting their baby to stop crying.

    • The Jiminy Conjecture
      Season 3 - Episode 2
      Sheldon and Howard wager comic books over a cricket's species. Meanwhile, a less-than-perfect romantic night agonizes Leonard and Penny.
    • 5/4/09

      Leonard is torn between being honest or self-serving when Stuart asks his advice for an upcoming second date with Penny. Howard realizes there's a crucial error in a toilet he designed for the International Space Station.

    • The Guitarist Amplification
      Season 3 - Episode 7
      Leonard and Penny's first big fight sees Sheldon playing mediator due to childhood trauma that's left him with an inability to be around loud verbal conflicts.
    • The Extract Obliteration
      Season 6 - Episode 6

      Sheldon's play a game of Words With Friends with Stephen Hawking while Penny takes a community college course without telling Leonard.

    • The Vengeance Formulation
      Season 3 - Episode 9

      Barry Kripke pranks Sheldon during his spot on NPR, leaving him with a taste for vengeance. Howard, pressured by Bernadette to define their relationship, gets advice from a fantasy version of Katee Sackhoff.

    • The Psychic Vortex
      Season 3 - Episode 12

      Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Raj in picking up a girl at a university party.

    • The Bozeman Reaction
      Season 3 - Episode 13

      A robbery of their apartment sees Leonard and Sheldon call on their friends to devise a security system.

    • The Love Car Displacement
      Season 4 - Episode 13

      A science convention at a hotel leads to Bernadette running into an ex-boyfriend and Howard worrying he can't quite compare.

    • The Hot Tub Contamination
      Season 10 - Episode 5
      Sheldon and Amy start to get on each other's nerves due to living together, so Leonard and Penny try to think of a way for them to cool off. Meanwhile, Howard and Bernadette spy on Raj and Stuart after the two sneak in to use their hot tub.
    • The Recollection Dissipation
      Season 10 - Episode 20

      Sheldon wakes up with no memory of what he did due to taking cold medicine and realizes that he lost his notebook which contains classified information about the air force project he's working on. Meanwhile, Bernadette starts to feel guilty about going back to work and leaving her baby, but she doesn't tell Howard about it which makes him believe that she's mad at him about something.

    • The Gyroscopic Collapse
      Season 10 - Episode 23

      Leonard, Sheldon and Howard celebrate the successful completion of their top-secret military project, until an unpleasant surprise leaves their heads spinning. Also, Raj moves out and Amy considers an offer of a summer position as a visiting researcher.

    • The Hofstadter Isotope
      Season 2 - Episode 20
      A fellow comic book enthusiast's hitting on Penny leads to Leonard, Raj, and Howard going to a bar's Ladies' Night.
    • The Spaghetti Catalyst
      Season 3 - Episode 20
      Subsequent to Leonard and Penny's break-up, Sheldon tries to hide from Leonard and the gang that he had a friendly spaghetti dinner at Penny's.
    • The Proposal Proposal
      Season 11 - Episode 1

      Season 11 begins with Amy giving Sheldon an answer to his marriage proposal. Meanwhile, Howard and Bernadette struggle with some unexpected news.

    • The Vartabedian Conundrum
      Season 2 - Episode 10
      Leonard seeks Penny's counsel when his relationship with Stephanie takes off faster than he'd like. Sheldon's hypochondriac tendencies get the better of him.
    • The Platonic Permutation
      Season 9 - Episode 9

      Leonard and Penny cook their first Thanksgiving dinner as a married couple, Sheldon and Amy, as friends, visit an aquarium and Howard, Bernadette, Raj and Emily volunteer at the local soup kitchen.

    • The Killer Robot Instability
      Season 2 - Episode 12
      Penny's criticism of Wolowitz's romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for.
    • The Large Hadron Collision
      Season 3 - Episode 15
      Leonard faces a dilemma in choosing between Sheldon or Penny to accompany him to Switzerland to see CERN's Large Hadron Collider on Valentine's Day.
    • The Herb Garden Germination
      Season 4 - Episode 20
      Sheldon and Amy decide to start rumors about themselves as a social test. Meanwhile, Howard takes his relationship with Bernadette to an even higher level.
    • The Separation Agitation
      Season 10 - Episode 21
    • The Imitation Perturbation
      Season 12 - Episode 6

      When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween party. Also, Leonard is shocked that Penny doesn't remember their first kiss.

    • The 21-Second Excitation
      Season 4 - Episode 8
      The guys camp out in line to see a print of Raiders of the Lost Ark with 21 extra seconds and are outraged to see Wil Wheaton and his friends being allowed to skip the line. Penny and Bernadette invite Amy to their girls night.
    • The Cognition Regeneration
      Season 10 - Episode 22

      Penny's job offer from a former boyfriend doesn't sit well with Leonard.

    • The Collaboration Contamination
      The Collaboration Contamination
      Season 11 - Episode 5

      Sheldon and Amy are concerned when Howard and Amy collaborate on a project and spend a lot of time together. Leonard and Penny come up with a way to deal with Sheldon.

    • The Conference Valuation
      Season 12 - Episode 17

      Penny and Bernadette go to San Diego for a pharmaceutical sales convention, leaving Howard in charge of the kids. Also, Sheldon finds a book on experimenting on kids, and the guys plus Amy make a day of it.

    • The Separation Triangulation
      Season 11 - Episode 14

      Raj discovers that the woman he is dating is still married and has only been separated for two weeks; Sheldon rents his old room for a quiet place to work.

    • The Relaxation Integration
      Season 11 - Episode 3

      Sheldon and Amy struggle with setting a wedding date while Raj and Stuart fight for date with Bernadette's new co-worker.

    • The Cornhusker Vortex
      Season 3 - Episode 6

      Leonard, hoping to fit in with Penny's football-loving friends, gets tutored in the sport by Sheldon. Raj is infuriated when Howard's skirt-chasing leads to the loss of his prized patang.

    • The Wheaton Recurrence
      Season 3 - Episode 19
      Sheldon gets to square off on the bowling alley against nemesis Wil Wheaton. Meanwhile, Leonard's miffed when Penny doesn't respond the way he hoped after saying, "I love you."
    • The Friendship Contraction
      Season 5 - Episode 15

      Leonard can't take Sheldon's continued selfishness and agrees to dissolve the Roommate Agreement. Howard wants to have a cool nickname for when he's an astronaut.

    • The Hesitation Ramification
      Season 7 - Episode 12
      Penny turns to Leonard for comfort after her guest appearance on NCIS does not turn out well. She ends up putting Leonard on the spot regarding their relationship. Sheldon works on his sense of humor and Raj practices talking to girls.
    • The Athenaeum Allocation
      Season 11 - Episode 17

      Leonard works hard to help secure the perfect wedding venue and date for Sheldon and Amy. Also, Howard and Bernadette have a hard time deciding who should stay at home with the kids and who should go back to work.

    • The Focus Attenuation
      Season 8 - Episode 5

      While Amy, Penny and Bernadette have a girls weekend in Vegas, Penny ends up having to study at the last minute, while Amy and Bernadette go out and get drunk. Back at home, with the girls gone, the four guys want to invent something new, but keep focusing on other things.

    • The Space Probe Disintegration
      Season 8 - Episode 12

      While Raj eagerly awaits data from a space probe in which he was involved, Howard keeps distracting him. Later, dress shopping with Penny and Amy doesn't exactly prove to be a good fit for Leonard and Sheldon.

    • The Hot Troll Deviation
      Season 4 - Episode 4
      Wolowitz tries to get back together with Bernadette. Sheldon and Raj go to war at the university.
    • The Tenant Disassociation
      Season 11 - Episode 19

      When Leonard learns Sheldon is the president of the tenants association, he decides to run against him. Also, Bernadette encourages Howard and Raj to find the owner of a drone they found in the backyard.

    • The Pulled Groin Extrapolation
      Season 5 - Episode 3
      Leonard escorts Amy to a wedding. Meanwhile, Howard convinces Bernadette to spend the weekend with him at his mother's house as a trial run, and Sheldon gets involved in model trains.
    • The Birthday Synchronicity
      Season 10 - Episode 11

      The time comes for Howard and Bernadette to have their baby and the gang all wait together at the hospital. Meanwhile, it is Amy's birthday and she and Sheldon plan on having their annual night of romance.

    • The Precious Fragmentation
      Season 3 - Episode 17
      The discovery of a prop ring from The Lord of the Rings movies puts a strain on the guys' friendship.
    • The Donation Oscillation
      Season 12 - Episode 15

      Leonard has second thoughts about helping Zack and Marissa have a baby. Also, Howard, Bernadette, Raj and Anu turn Raj's canceled bachelor party into a couple's trip aboard the "vomit comet."

    • The Anxiety Optimization
      Season 8 - Episode 13

      Sheldon becomes concerned that his cushy lifestyle is impacting his professional progress and keeping him from achieving scientific renown, so he asks the gang to make life more difficult for him. Meanwhile, Howard invents an unflattering game about Raj.

    • The Skywalker Incursion
      Season 8 - Episode 19

      A speaking engagement at UC Berkeley puts Leonard and Sheldon in a galaxy not too far, far away from their idol George Lucas' Skywalker Ranch, and they consider dropping by. Meanwhile, Howard and Bernadette argue over what to do with his Doctor Who TARDIS, so Raj and Amy try to settle things with a game of table tennis.

    • The 2003 Approximation
      Season 9 - Episode 4

      When Leonard and Penny move in together, Sheldon is very upset and longs for an emotion-free life like what he had in 2003. Meanwhile, Howard and Raj attempt to form a band.

    • The Allowance Evaporation
      Season 10 - Episode 16

      Amy is incensed when she discovers Sheldon has shared intimate relationship information with people at the university; and Raj is knocked for a loop when his father stops sending financial support.

    • The Romance Recalibration
      Season 10 - Episode 13
      After Penny feels Leonard is taking her for granted, she decides to go on a spa weekend with Amy instead of Leonard leaving Sheldon to play the unlikely peacemaker. Meanwhile, Howard and Raj try to fix a squeaky floorboard in the baby's room.
    • The Application Deterioration
      Season 9 - Episode 18

      When filing for a patent for their infinite persistence gyroscope, Leonard, Sheldon, and Howard learn that the university owns 75% of the patent's revenue, so they decide to write a contract between the three of them to split the remaining 25%. Also, Raj looks to the ladies for advice when both Emily and Claire contact him.

    • The Irish Pub Formulation
      Season 4 - Episode 6
      When Raj's sister has a one-day layover he forbids the others from hooking up with her, unaware she and Leonard already did long ago.
    • The Benefactor Factor
      Season 4 - Episode 15
      After meeting at a fundraising gala, an aged, but wealthy, Caltech donor makes Leonard ponder if he's willing to have sex with her to secure another donation.
    • The Boyfriend Complexity
      Season 4 - Episode 9
      When Penny's father visits, she gets Leonard to pretend to still be her boyfriend. Meanwhile, Howard, Raj, and Bernadette spend the night on an astronomy project.
    • The Alien Parasite Hypothesis
      Season 4 - Episode 10

      Amy crushes on one of Penny's dim ex-boyfriends, Zack. Raj and Howard argue over who'd be the better superhero.

    • The Rothman Disintegration
      Season 5 - Episode 17

      When a new office space is made available, Sheldon goes head to head with his nemesis, Kripke, for the right to move in. Meanwhile, Penny is unsettled by painting given to her by Amy.

    • The Retraction Reaction
      Season 11 - Episode 2

      Leonard angers the university and the entire physics community when he gives an embarrassing radio interview. Meanwhile, Amy and Bernadette bond over having to hide their success from Sheldon and Howard.

    • The Line Substitution Solution
      Season 9 - Episode 23

      Wanting to go out with the guys, Sheldon foolishly pays Stuart to spend the day with Amy. Also, Penny struggles to connect with her new mother-in-law while Amy and Bernadette have no problem hitting it off with her.

    • The Big Bear Precipitation
      Season 9 - Episode 20

      While out at a cabin in the woods, Sheldon, Leonard, Penny and Amy play a game of "Never Have I Ever" which reveals some of their deep dark secrets. Meanwhile, Howard starts to believe that Raj is getting way too involved with Bernadette's pregnancy and tries to think of the nicest way to tell him to stop.

    • The Paintball Scattering
      Season 12 - Episode 11

      Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Raj catches Anu with her ex-boyfriend, and Stuart doesn't want to move in with Denise.

    • The Sales Call Sublimation
      Season 9 - Episode 12

      Leonard helps Penny get an appointment with a psychiatrist in order to help her make a sale; after two years, Stewart moves out of Howard and Bernadette's house into his own apartment. Elsewhere, Sheldon and Raj discover a medium sized asteroid, then debate about what to call it.

    • The Laureate Accumulation
      Season 12 - Episode 18

      Competitors Pemberton and Campbell charm America on a publicity tour, so Sheldon and Amy try to bring Nobel laureates Kip Thorne, George Smoot and Frances Arnold to their side. Also, Halley's fear of the dark leads to opportunity and conflict for Howard, Bernadette and Stuart.

    • The Clean Room Infiltration
      Season 8 - Episode 11

      On Christmas Eve, Amy plans a traditional Victorian dinner, while Raj, Leonard and Howard scramble to remove a pigeon that flew into the clean room at the university. To prove a point to Amy, a Scrooge-like Sheldon buys her the worst possible gift.

    • The VCR Illumination
      Season 12 - Episode 10

      Sheldon and Amy are still down about their theory being disproven, but a VHS tape from Sheldon's past inspires him not to give up. Also, Bernadette turns into a pageant mom when she tries to help Howard ace his Magic Castle audition.

    • The Fortification Implementation
      Season 8 - Episode 20

      When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Wolowitz meets the half-brother he never knew he had, and when Penny is invited to appear on Wil Wheaton's podcast, she and Leonard have a huge, on-air argument.

    • The Hook-Up Reverberation
      Season 8 - Episode 4

      Raj's brings his new girlfriend over to meet the gang, but she seems standoffish with Penny, who tries to figure out why. Meanwhile, the guys put their heads together to try to re-open Stuart's comic book store.

    • The Graduation Transmission
      Season 8 - Episode 22

      When Leonard is set to give the commencement address at his former high school, a canceled flight threatens to stop him giving the speech. Meanwhile, Howard's engineering skills are tested when he and Sheldon try fix Raj's toy helicopter, while Raj plays his parents against each other after his father cuts him off financially.

    • The Locomotion Interruption
      Season 8 - Episode 1

      In the Season 8 premiere, Amy and Leonard take a surprise road trip to Arizona to retrieve Sheldon, while Penny goes on a job interview at Bernadette's company, and Howard has problems wrapping his head around Stuart's relationship with Mrs. Wolowitz.

    • The Celebration Experimentation
      Season 9 - Episode 17

      Sheldon has always hated birthdays due to many bad experiences when he was younger, so the gang tries to throw him the best birthday party ever, which includes getting Adam West to appear at the party.

    • The Fermentation Bifurcation
      Season 9 - Episode 22

      The gang goes to a wine bar and runs into Penny's old boyfriend, Zack, who hits it off with Raj's girlfriend, Claire. Meanwhile, Bernadette and Sheldon spend an evening together.

    • The Fetal Kick Catalyst
      Season 10 - Episode 6

      Feeling his fetal offspring kick sends Howard on a baby-items buying binge with Raj; Sheldon and Amy host a brunch in their new digs; and Penny, by virtue of her performance in Serial Ape-ist, is invited to a sci-fi convention.

    • The Confirmation Polarization
      Season 12 - Episode 13

      Sheldon and Amy's super asymmetry theory is proven by two physicists, Dr. Pemberton and Dr. Campbell from Chicago, who then try to kick Amy off the Nobel nomination. Also, Bernadette has a big success at work and Penny's going to be a part of it—whether she wants to or not.

    • The Property Division Collision
      Season 10 - Episode 10

      Sheldon and Leonard fight when it comes to dividing up their joint possessions while Raj and Stewart trip over themselves in helping Bernadette during the final weeks of her pregnancy.

    • The Citation Negation
      Season 12 - Episode 9

      Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been discovered and disproven. Also, ultra-competitive Bernadette asks Stuart's girlfriend, Denise, to teach her how to beat Howard in a popular video game.

    • The Excelsior Acquisition
      Season 3 - Episode 16
      An appearance in traffic court comes at the worst possible time for Sheldon—the same day Stan Lee is appearing at the comic book store.
    • The Desperation Emanation
      Season 4 - Episode 5
      Leonard is depressed to realize all the other guys have girlfriends, while he doesn't. Amy wants to introduce Sheldon to her mother.
    • The Colonization Application
      Season 8 - Episode 17

      There's trouble in paradise when Amy discovers Sheldon signed up for a one-way mission to colonize Mars, and the two get into a dogfight at a pet store. Meanwhile, Leonard makes a very "adult" purchase for Penny; and Emily catches Raj snooping in her apartment.

    • The Commitment Determination
      Season 8 - Episode 24

      In the Season 8 finale, Leonard and Penny are pressured to set a wedding date by Sheldon, whose relationship with Amy has taken an interesting turn.

    • The Empathy Optimization
      Season 9 - Episode 13

      After the entire gang was abused by a sick Sheldon, they plan a weekend getaway without him. Meanwhile Sheldon, in his own way, sets out to apologize to everyone he mistreated.

    • The Collaboration Fluctuation
      Season 10 - Episode 19

      Raj moves in with Leonard and Penny and a period of adjustment begins for the three, while the usually self-centered Sheldon shows surprising interest in Amy's work.

    • The Helium Insufficiency
      Season 9 - Episode 6

      As a Swedish team threatens to beat Leonard and Sheldon to proving their own theory, they consider breaking some rules in order to be able to make their experiment. Meanwhile, Penny and Bernadette set a dating app on Amy's phone.

    • The Vacation Solution
      Season 5 - Episode 16

      Forced to use his vacation time, Sheldon dabbles in biology in Amy's lab. Bernadette reveals to the girls that her father wants her to make Howard sign a pre-nup.

    • The Grant Allocation Derivation
      Season 12 - Episode 7

      Leonard is caught between a rock and a hard place when he's responsible for distributing extra grant money. Also, Bernadette turns the backyard playhouse into a hideaway from her husband and kids.

    • The Propagation Proposition
      Season 12 - Episode 12

      Penny's ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Raj attempts to mend things with his ex-fiancée, Anu.

    • The Bus Pants Utilization
      Season 4 - Episode 12
      Their friendship becomes strained when Sheldon tries to take over Leonard's creation of a smartphone application that solves differential equations.
    • The Separation Oscillation
      Season 9 - Episode 2

      Leonard and Penny are still having problems with their new marriage while Sheldon comes up with a few ways to get revenge on Amy for breaking up with him.

    • The Valentino Submergence
      Season 9 - Episode 15

      Sheldon and Amy host a live Valentine's Day episode of "Fun with Flags", Leonard and Penny look for a way to enjoy Valentine's Day, Howard and Bernadette prepare to try out their new hot tub and Raj struggles with his feelings about Emily.

    • The Speckerman Recurrance
      Season 5 - Episode 11

      Leonard is hesitant when a bully from high school wants to meet for a drink. Meanwhile, Penny comes to realize she was a bully herself.

    • The Wedding Gift Wormhole
      Season 12 - Episode 2

      Sheldon and Amy drive themselves crazy trying to figure out what "perfect gift" Leonard and Penny gave them for their wedding. Also, Raj decides he wants to settle down and asks his father to arrange a marriage for him.

    • The Champagne Reflection
      Season 8 - Episode 10

      Leonard, Raj and Howard clean out the office of the deceased Professor Roger Abbot and find a bottle of champagne meant to be opened when he made his first great scientific discovery. Meanwhile, Sheldon prepares his final episode of "Fun with Flags". Bernadette discovers that people are afraid of her.

    • The Viewing Party Combustion
      Season 9 - Episode 21

      While arranging a Game of Thrones viewing party for the gang, a small disagreement between Leonard and Sheldon turns into a major deal and ends up with part of the group at Leonard's and the rest at Penny's.

    • The Planetarium Collision
      Season 12 - Episode 5

      Amy doesn't have time to work on super-asymmetry, so Sheldon goes to great lengths to ensure she's available to work with him even if it means accidentally sabotaging her career in the process. Also, Raj doesn't want Howard to join him in hosting a show at the planetarium.

    • The Meteorite Manifestation
      Season 12 - Episode 14

      Sheldon helps Howard and Bernadette navigate city hall bureaucracy; Leonard is jealous when he discovers that Raj and Bert excluded him from a scientific project.

    • The Meemaw Materialization
      Season 9 - Episode 14

      Sheldon's grandmother, aka Meemaw, visits and there's friction between her and Amy, which intensifies after the elderly woman blurts out a secret about Sheldon. Meanwhile, Raj is conflicted when an attractive writer for a children's sci-fi show asks to collaborate with him.

    • The Solder Excursion Diversion
      Season 9 - Episode 19

      Sheldon's old laptop finally dies and Amy buys him a new one. Sheldon does not want to dispose of the old one so he takes it somewhere where he knows it will be safe. Meanwhile, Leonard and Howard sneak off to see a preview of Suicide Squad, leaving their wives to work on a project they were busy on.

    • The Conjugal Configuration
      Season 12 - Episode 1

      In the Season 12 premiere, Sheldon and Amy's honeymoon runs aground in New York, while Penny and Leonard discover they are uncomfortably similar to Amy's parents. Also, Raj insults physicist Neil deGrasse Tyson and starts a Twitter war.

    • The Communication Deterioration
      Season 8 - Episode 21

      When Raj is asked to submit a proposal to NASA, the guys end up in a fight. Penny wonders what to do when she asked to audition for a movie role.

    • The Lunar Excitation
      Season 3 - Episode 23
      Howard and Raj try to find the perfect match for Sheldon by setting him up on an Internet dating site. Seeing her moronic new boyfriend interact with the gang makes it abundantly clear to Penny that she can't go back to dating stereotypical dumb jocks after dating Leonard.
    • The Leftover Thermalization
      Season 8 - Episode 18

      An electrical short thaws the last meal that was cooked by Mrs. Wolowitz, and the gang ponders what to do with it, while Sheldon and Leonard's work is featured in a magazine, but only one receives credit.

    • The First Pitch Insufficiency
      Season 8 - Episode 3

      A nervous Wolowitz is thrown for a loop when NASA asks him to toss out the first pitch at a Los Angeles Angels baseball game. Meanwhile, Sheldon brags that he and Amy are a better couple than Leonard and Penny, so they set out to prove he's way off base.

    • The Apology Insufficiency
      Season 4 - Episode 7

      The rest of the gang is interviewed by the FBI for Howard's security clearance, with Sheldon accidentally letting slip some damaging information.

    • The Positive Negative Reaction
      Season 9 - Episode 16

      Bernadette shares with Howard that she's pregnant, but his reaction is not what she hoped for. The guys take Howard to a karaoke bar where they are joined by the girls to celebrate the news.

    • The Procreation Calculation
      Season 12 - Episode 3

      The Wolowitz's life gets complicated when Stuart starts bringing his new girlfriend home. Also, Penny and Leonard talk about starting a family while Raj explores an arranged marriage.

    • The Engagement Reaction
      Season 4 - Episode 23
      Mrs. Wolowitz ends up in the hospital after Howard tells her he's marrying Bernadette. While there, Leonard stresses over Penny and Priya warming up to one another.
    • The Friendship Algorithm
      Season 2 - Episode 13
      Looking to get friendly with Barry Kripke to gain access to a piece of high-tech lab equipment, Sheldon develops a flowchart process to make friends.
    • The Consummation Deviation
      Season 12 - Episode 8

      Sheldon tries to bond with Amy's father, but when Wolowitz lures Mr. Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs. Fowler. Also: Raj and Anu try to get physical for the first time.

    • The Tam Turbulence
      Season 12 - Episode 4

      Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, so Leonard takes matters into his own hands. Also, Bernadette and Penny take out Raj's fiancée, Anu, for dinner to get the skinny on her.

    • The Matrimonial Momentum
      Season 9 - Episode 1

      Penny and Leonard deal with Leonard's confession on the way down the aisle while Sheldon struggles to understand Amy's decision to take a step back from their relationship.