Penny: So, who is she?
Leonard: Oh, she's a doctor.
Penny: Oh, nice. A doctor doctor, or a you kind of doctor?
Leonard: Doctor doctor. Surgical resident. Smart, pretty. Let me ask you something. If your friend thinks he's dating someone, but he's not because, in fact, you're dating her, does that make you a bad person?
Penny: Well, that depends.
Leonard: On what?
Penny: Is that friend Wolowitz?
Leonard: Yeah.
Penny: Screw him. You're fine.

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?

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Mrs. Wolowitz Tell her we're going to the Olive Garden. I have a coupon from the paper.
Howard: We're not going to the Olive Garden, ma!
Mrs. Wolowitz Oh, Mr. Big Shot with his Red Lobster.

Stephanie: So, how was your day?
Leonard: You know, I'm a physicist, I thought about stuff.
Stephanie: That's it?
Leonard: I wrote some of it down.