Penny: Is everything okay?
Leonard: No, I found a paper that proves their theory wrong. They thought this was gonna be their Nobel Prize. It's gonna break his heart.
Penny: Oh, man. Maybe leave an anonymous note, you know, like in high school, when you want to let your best friend know that her boyfriend's cheating on her.
Leonard: Why wouldn't you just tell her that?
Penny: I don't know. Maybe you had a hickey.
Leonard: Isn't it better to get bad news from a friend?
Penny: Trust me, it's not. I went to prom with a hickey and a black eye.

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.

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

Bernadette: Hey, Denise. Is Stuart here?
Denise: Oh, no. Doctor's appointment.
Bernadette: Oh, is he okay?
Denise: Not since I've known him.

Sheldon: You know we're almost finished with our paper; we just need help tracking down the citations.
Leonard: That's busywork. Can't you just get a grad student to do it?
Amy: No, this paper is incredibly important to us, and we need someone we can trust.
Please, it would mean a lot.
Leonard: You know what? Sure. The three of us in the library looking up old papers, that actually could be kind of fun.
Sheldon: Oh, no, we won't be there.
Leonard: It just got more fun.

Sheldon: I suppose you're wondering why I put you through all this.
Leonard: You mean the last two minutes or the last 20 years?