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.

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

Penny: At one point, they had me figure out how to get a banana out of a puzzle box.
Leonard: Wait, Sheldon gave me a banana in a box. He was testing me, too.
Penny: Unbelievable.
Leonard: And how could a chimp even solve that? That was impossible.
Penny: Really? You couldn't get it out?

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

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.