Sheldon: Do you think your father's doing unspeakable things to my mother?
Leonard: No.
Sheldon: Are you saying that because the things are unspeakable?
Penny: Your parents are old. Anything unspeakable was finished by 9:30.

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?

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Raj: Can we take a moment to discuss that I just lied to the government for you?
Howard: Yeah, I would not have done that for you.

Bernadette: Love is patient, but it's not gonna put up with all the side chatter, so let's knock it off!
Howard: At least she's yelling at someone else for a change.
Bernadette: Howard!