Leonard: Are you sure?
Penny: Well, have you slept with her yet? ... You dog! Good for you.
Leonard: Does that change things?
Penny: No.
Leonard: So why'd you ask?
Penny: I'm nosy. See ya.

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.

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

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.