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?

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

Penny: Sheldon, what did we say about being a nicer friend?
Leonard: Thank you.
Penny: Leonard, what did we say about being a gullible weeny?

Leonard: What am I supposed to do?
Penny: Err, keep your mouth off other women.

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.

Amy: After a lively debate, that motion passed by a 2-0 margin.
Leonard: It's nice to see a busy couple keep the spark of bureaucracy alive.