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?

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

Raj: [to Amy] If you were having Sheldon's baby, would you really want him in the room?
Penny: Yeah, if he's in the room when they're making the baby, I'll give you $10.

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?

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.