How I Met Your Mother

This episode starts off with future Ted telling his kids about their Uncle Barney, and how mysterious he was. None of them had ever stepped foot into his apartment until one day...
We see Barney wake up in bed with Lily and he starts screaming which causes Lily to start screaming.
Future Ted explains that it's a good story, and alcohol had nothing to do with it.
2 Weeks Earlier at Lily's Housewarming

Lily is welcoming Ted and Robin into her very cramped apartment. The toilet and bathtub are literally in the kitchen, also her fold from the wall bed doesn't even fit into her 'bed room'.
McLaurens

Ted, Robin and Barney are trying to figure out ways to get Lily out of that apartment. Lily can't stay with Robin because Lily's allergic to dogs, and she can't stay with Ted, because she's allergic to Marshall. They ask Barney to let her stay there, but Barney says no way.

Marshall enters asking if anyone would like his spare ticket to the Alanis Morisette show, which everyone declines. His spare ticket used to be for Lily. He then expresses how much he misses being in a couple and being able to go out and do couple things, such as brunch. He's tried to go eat brunch alone, but the host just laughed at him and caused Marshall to run out.
Barney's Apartment

(For those who didn't catch the episode, its mostly black leather and silver, with a mini golf set in the living room and a life Storm Trooper in the back of the room)

Barney walks in on the phone with his mother (a bookie), and realizes that Lily is sitting on his couch. She then explains that she would never be there, except that earlier when she was trying to pull down her folding bed, she ended up pulling down the wall it was connected to, and being able to look into her neighbor's living room.

Lily asks if she can stay, but Barney says he has no room. Lily says that he has more than enough room, he lives in a 2 bedroom apartment, where one of the beds its just for his suits. After some talking, Barney finally allows Lily to stay for 2 days, but his rule is that she's not allowed to change anything.
Ted and Marshall's Apartment

Marshall comes home, and Ted and Robin are in the living room. He's just come home from the Alanis Morrisette concert with a friend Brad, who was also recenty dumped.
Flashback to McLaurens

Marshall and Brad walk in fresh from the concert and talk about Brad's break up. Marshall invites Brad to brunch.
Back to Ted and Marshall's Apartment

Ted and Robin are surprised that Marshall invited a guy to brunch and make fun of him.
Barney's Apartment

It's morning and Lily is making breakfast and hands Barney a plate, he then in turn, dumps the contents into the trash. Barney is upset that she already broke the rule of changing things. Barney sees that having food in the fridge, and having hot coffee are signs of a relationship, something he doesn't want. He then takes Lily on tour of what makes his apartment tell women that it is a place to leave, not stay.
Barney's Bedroom

He tells her that he has a king bed, but a full blanket and one pillow. This is telling the girl that their work is done.
Barney's Bathroom

He has only one towel, and no hairdryers. His toilet also doesn't allow the seat to stay down, if you put the seat down, it springs back up.
Barney's Hallway

Barney shows his bookshelf full of porn, and pushes a button that turns the lights red, and plays porn type music.
Pop Over Pantry, Brunch

Marshall and Brad are having brunch and expressing how much they love it. Brad then invites Marshall to see "Mamma Mia" on broadway.
Barney's Bedroom

Barney wakes up with a blonde in his bed, who is already awake and watching him sleep. He asks if the cold kept her up, since he only has a full blanket. But she says no, she's been watching him sleep. He apologizes that he didn't have enough towels for her if she tried to shower. She says she doesn't believe in taking showers everyday. He then apologizes for not having coffee if she wanted anyway. She tells him she's boycotting coffee. She also tells him that she loves the place, and is happy she's unemployed because she could spend the entire day there, which freaks Barney out. He takes her to his "book shelf" and lights up the porn. Instead of freaking her out, she's happy he's able to display his sexual side, and blurts out that she loves him. Which is now freaking Barney out, and he backs up into the kitchen.
Lily opens the front door, and starts talking to Barney, but stops when she realizes Barney has a guest. The blonde sees Lily is assumes she is Barney's wife and starts asking him questions. At first Barney says no, but realizes the chance he has and says yes. This way the blonde is finally upset, and leaves his place. Barney is so thrilled with the result, he tells Lily that she's not going to go anywhere. Barney then explains to her about the crazy blonde, and asks her to stay and pretend to be his wife for the occasional one night stands. Lily agrees right away.
McLaurens

Ted, Robin and Marshall are at a table, and Ted cannot believe that Brad asked Marshall to see "Mamma Mia." At first Marshall is trying to defend the invite. Ted makes fun of it and calls it a third date, and Marshall tells them they're supposed to have dinner before the show, at Cafe L'Amour. Robin and Ted make fun of the entire idea, while Marshall defends himself and the fact that they're threatened that a single guy can do "couple" things.
Barney's Kitchen

He's having an actual breakfast (eggs,toast, coffee), with a brunette. He asks her to pass the "Arts & Liesure" part of the newspaper, which is apparently Lily's cue to enter. She comes in, and says "Honey, I'm home!" She then feigns surprise and anger, and asks Barney what's going on. They confont each other, Barney saying he could explain, but Lily slaps him anyway, telling him she can't believe she worked as a stripper to get him through medical school. The brunette apologizes, and Lily tells her to get out, which she does right away. Once the door closes, Lily stops, and everything is normal. Barney is amazed at her performance. They both sit and eat the breakfast. Barney confesses that he actually likes having food around. Lily proposes that they make the apartment a little more "homely" as if a woman lived there.
Musical Montage of changing Barney's Apartment

Colorful pillows are thrown on the couch.

Barney rolls up his mini golf, and Lily replaces it with a rug.

Lily replaces his life- storm trooper with a plant.

Lily buys fruits and flowers for the kitchen.

Lily takes down half of the porn shelf, and replaces it with actual books.
Ted and Marshall's Apartment

Robin and Ted are watching tv, and Marshall comes home. They make fun of Marshall's date, which at first Marshall denies the date. But he then confesses that yes, it was a date, and it got way weird.
Flash back to Cafe L'Amour

Brad pays for dinner, and Marshall says that that is unneccessary, but Brad insists. Brad tells Marshall he has chocolate on his chin, after Marshall misses cleaning it off, Brad licks his napkin, and cleans it off for him.
Ted and Marshall's Apartment

Ted is totally surprised at that part of information. Marshall tells them it gets worse.
Flash back to Cafe L'Amour

Brad is helping Marshall put his suit jacket back on. Brad then asks Marshall to go to a wedding with him.
Ted and Marshall's Apartment

Ted and Robin try to tell him its ok, they'll just be two single guys on the prowl. Marshall tells them, it gets worse.
Flash back to Cafe L'Amour

Brad is fixing Marshall's collar, while Marshall is obviously uncomfortable. He tells Marshall that the wedding is all the way in Vermont, and that they're staying at a Bed and Breakfast that he and his ex girlfriend used to frequent. He also tells Marshall that they'll be sharing a room. Marshall looks horrified. Marshall says no, and Brad says he understands, and starts explaining that this is the first time seeing his college friends since his girlfriend left him, and starts crying because he misses her. Marshall says he'll go with him. Brad is excited and says they can go half on the wedding gift, he was thinking a gravy boat.
Ted and Marshall's Apartment

Ted and Robin can't help but laugh, and Marshall is asking them if they think Brad is crazy. Ted says he's not crazy, he's just going through girlfriend withdrawal, and Marshall is there to help. Robin advises Marshall that they need to break up. Marshall agrees.
Barney's Bedroomn

Barney and Lily are making Barney's new bed, with new sheets, pillows and blankets. Lily jumps into the bed to try out the new sheets, while Barney gets ready to leave. He asks her what she'll be doing, and she says she's just going to stay in and watch tv. Barney the decides to watch a bit of tv with her.
Next morning, in the NYC streets

Marshall is walking down the street to meet up with Brad for the wedding. He sees Brad waiting on the corner with flowers. Marshall freaks out, and calls Ted that Brad got him flowers. All Ted and Robin do is laugh, so Marshall hangs up and approaches Brad. He tell's Brad that its not cool that he got him flowers, when a girl comes up to Brad and says "Hi sweetie" Brad hands Kara the flowers, and Marshall asks if they're back together, which they are. Marshall then looks hurt, and Brad apologizes for not telling him sooner, since Kara will now be his date to the wedding. Marshall walks away. Kara asks Brad what's up with Marshall, and Brad says, that he thinks Marshall is in love with him.
Barney's Bedroomn

We again see Barney wake up in bed with Lily and he starts screaming which causes Lily to start screaming. Barney cannot believe that he is in bed with Lily and that they possibly had sex. But Lily says they didn't, they just fell asleep. Barney says that is impossible, he does not sleep in the same bed with a woman and not make a move. He blames her, and says she spooned him against his will, and gets out of bed, freaked out. He tells her they've done all these "relationship type" things, and freaks out even more. Lily tells him that Barney is just scared of letting people in, and that he shouldn't blame her. He tells her she has to leave, and Lily starts yelling that he can't just kick her out. And an argument insues betweent he happy "couple" and the part their ways
In the end, Lily received all the furnishing they bought for his place to put into hers.