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

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

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?

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

Penny: Wait, what is wrong with you two? He was talking about television during their date night.
Sheldon: Oh, not just date night. Our 5th anniversary.
Penny: Okay, see, that's even dumber than you wondering if being bitten by a goat would give you the powers of a goat.
Sheldon: If that happens, don't make me wait ten years to watch you eat a tin can.

Sheldon: Amy's mad at me, and I'm not clear why.
Penny: Okay, were you talking before she got upset?
Sheldon: Yes.
Penny: That's probably it.

Penny: Hey, I don't think she's wrong about you going too slow in the relationship.
Sheldon: Too slow?
Penny: Yeah, you've been going out for years. You haven't even slept together.
Sheldon: That's right. It's called foreplay.