Penny: Well, a relationship is more complicated than a french fry.
Sheldon: Not according to the work of Berscheid, Snyder & Omoto.
Penny: Oh, what did those rascals do now?

Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Penny: I mean, who even reads Scientific American?
Leonard: It's kind of a big deal.
Penny: If it's such a big deal, how come the biggest celebrity they could get for the cover is a molecule?

Howard: I'm not signing a prenup.
Penny: All right, Howard Wolowitz, listen up! You sign anything she puts in front of you, because you are the luckiest man alive. If you let her go, there is no way you can find anyone else. Speaking on behalf of all women, it is not going to happen, we had a meeting.

Sheldon: Ignore them, Amy. They're just jealous because they'll never have a relationship as good as ours.
Penny: Isn't this when he says "bazooka" or something?

Penny: You guys are going out two nights in a row?
Sheldon: I missed a number of date nights while I was on my train trip, and I'm contractually obligated to make them up under the terms of the relationship agreement.
Penny: That's so hot.
Amy: It's better than hot, it's binding!

Leonard: I've seen you guys ignore each other for hours, doing totally different things.
Sheldon: It's called parallel play.
Leonard: Yeah, toddlers do that.
Sheldon: Not as well as we do.