Penny: Hey, I think I know how you did the card trick.
Sheldon: Oh. Oh, please. If I don't know, you don't know. That's axiomatic.
Penny: Come here. (Whispers theory to Howard)
Howard: You're right.
Penny: Not too bad for someone who doesn't know what axiomatic means.

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?

Penny: Oh, big deal. Not knowing is part of the fun.
Sheldon: "Not knowing is part of the fun." Was that the motto of your community college?

Rajesh: Why so glum, chum?
Sheldon: Apparently you can't hack into a government supercomputer and then try to buy uranium without the Department of Homeland Security tattling to your mother.

Sheldon: So, you're saying this is a regulation deck?
Howard: I'm saying believe in magic, you muggle.