Sheldon: It's actually based on a very sound thesis. His mother published a paper on it.
Penny: What was it called? "I hate my son and that's why he can't have cake"?

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.

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

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

Howard: Try telling him it's a non-optional social convention.
Penny: What?
Howard: Just do it!
Penny: It's a non-optional social convention.
Sheldon: Oh, fair enough.
Howard: He came with a manual.

Sheldon: What computer do you have? And please don't say a white one.

Store Clerk: Excuse me, Sir, you don't work here.
Sheldon: Yes, well apparently neither does anyone else.