Leonard: Not only did Sheldon save my life, he didn't rat me out to the landlord. Or the police. Or Homeland Security.
Penny: Okay, so, basically, you're the reason I have to walk up and down three flights of stairs every day?

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

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.

Sheldon: This is the temperature you agreed to in the roommate agreement.
Leonard: Aw, screw the roommate agreement!
Sheldon: No, you don't screw the roommate agreement. The roommate agreement screws you.

Mrs. Wolowitz Howard, are you having a playdate?
Howard: I don't have playdates. I have colleagues.
Mrs. Wolowitz Do their parents know they're here?
Howard: No, but if you keep screaming, maybe they'll hear you.

Leonard: You know what, go to Hell and set their thermostat.
Sheldon: I don't have to go to Hell. At 73 degrees, I'm there already!