Penny: Can I tell you a secret?
Raj: Yeah.
Penny: I screwed up. Leonard's a great guy. Never should have broken up with him.

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: What do you mean new roommate? What happened to Leonard?
Sheldon: The same thing that happened to Homo Erectus. He was replaced by a superior species.
Raj: I'm the new homo in town.

Penny: So that means, you're a doctor, you're a doctor, you're a doctor, you're a doctor and, Howard, you know a lot of doctors.

Sheldon: Here's an interesting fact about alcohol: Man is not the only species that ferments fruit in order to become intoxicated. Can you guess what the other is? Hint: sometimes they pack the alcohol in their trunks.
Penny: Monkeys.
Sheldon: When does a monkey have a trunk?
Penny: When a suitcase just won't do.