The foam-forming chemical reaction that Sheldon uses to revenge Kripke is a famous experiment known as "Elephant toothpaste". It can be performed premixing concentratedhydrogen peroxideand a liquid detergent (Sheldonuses dish soap), and then mixing the above with a catalyst (Sheldon uses saturatedsodium iodide solution) that causes rapid decomposition of hydrogen peroxide. The decomposition produces large amount of oxygen and heat; foams are formed due to the liquid detergent and the released oxygen, while the heat causes prominent expansion of the foams.
Sheldon: Biologically speaking, Howard is perfectly justified in seeking out the optimum mate for the propagation of his genetic line.
Wolowitz: Thank you, Sheldon.
Sheldon: And whether that propagation is in the interest of humanity is, of course, an entirely different question.
Leonard: You'd have a better shot with the three-breasted Martian hooker from Total Recall.
Howard: Okay, now you're just being unrealistic. Anyway, that movie was, like, 20 years ago. Imagine how saggy those things would be.
Sheldon: (about his appearance on NPR) My mother is very excited. She's convening her Bible study group to listen in and then pray for my soul.
Sheldon: All right. These are the talking points for my NPR interview tomorrow. I need to make sure that they're simple enough for the less educated in the audience to understand. Howard, look this over and tell me what's unclear to you.
Howard: Excuse me, I have a master's degree in engineering from the Massachusetts Institute of Technology. It required the completion of 144 units of grad work and an original thesis.
Sheldon: Yes. Look this over and tell me what's unclear to you.
(entering Sheldon and Leonard's apartment)
Howard: Greetings, homies, homette.
Penny: Why are you back from your date so early?
Howard: In romance, as in show business, always leave them wanting more.
Penny: What exactly does that mean?
Leonard: He struck out.
Sheldon: What are you talking about?
Leonard: The cultural paradigm in which people have sex after three dates.
Sheldon: I see, now are we talking about date, the social interaction, or date, the dried fruit?
(Sheldon lies on his bed, humiliated)
Leonard: Are you willing to admit defeat?
Sheldon: I never admit defeat.
Sheldon: However, on an unrelated topic, I'm never getting out of this bed again.
This episode's end titles has Chuck Lorre's Vanity Card #269.
Katee Sackhoff, who turned down the role that went to Summer Glau for "The Terminator Decoupling", tagged along when friend and Battlestar Galactica co-star Tricia Helfer filmed a guest spot on Chuck Lorre's other show, Two and a Half Men. Chuck approached Katee with the concept of her appearing as Howard's fantasy, which she accepted.
The Italian episode title is "La formula della vendetta", the French title is "La Formule de la vengeance", the German title is "Die Racheformel", and the Spanish and Mexican title is "La fórmula de la venganza", all exact translations.
International Airdates: Latin America: January 12, 2010 on Warner Channel; Australia: March 1, 2010 on Channel 9; United Kingdom: April 22, 2010 on E4; Finland: November 22, 2010 on Sub; Turkey: November 29, 2010 on CNBC-e; Czech Republic: December 15, 2010 on Prima COOL; Slovakia: October 27, 2011 on Markiza
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