*Penny enters the apartment without knocking*
Sheldon: Who is it? Hello, Penny. It's open, come in. Sarcasm.

Sheldon: Please. We're facing a far more serious problem than stray arachnids.
Leonard: It's not so bad.
Sheldon: Not bad? It's horrible. You hear stories about this things, but you never think it'll happen to you.
Leonard:So they steamed your dumplings. Get over it.

Sheldon: We have a bowl. Our keys are in the bowl. You should get a bowl.
Penny: I just don't understand; how can beautiful mind of Sheldon Cooper forget his keys in the first place?
Sheldon: I left them in the bowl.

Sheldon: This is to train for a three month expedition to the magnetic North Pole.
Penny: What?!
Sheldon: I don't know how that sentence could possibly confuse you, but to elaborate, I'm going to the Arctic Circle with Leonard, Wolowitz and Koothrappali.

Hooker: What's your name?
Raj: Rajesh Ramayan Koothrappali.
Hooker: Hello Rajesh Ram...Hello Rajesh.

Wolowitz: *After he fixed Sheldon's algorithm* Gee, why can't Sheldon get a friend?

Leslie: Hello men. Sheldon.

Penny: Um, you know it's kinda early. Do you wanna maybe come in for some coffee or something?
Stuart: Oh gee, its a little late for coffee isn't it?
Penny: Aw, you think coffee means coffee. That is so sweet.

Dr. Gablehauser: What colorful nickname did you call Dr. Cooper this time?
Leslie: Dr. Dumbass.

Penny: So, do you think that if Leonard and I keep dating, Leonard would get bored with me?
Sheldon: That depends.
Penny: On what?
Sheldon: Do you have a working knowledge on Quantum Physics?
Penny: No.
Sheldon: Do you speak Klingon?
Penny: No.
Sheldon: Do you know any card tricks?

Sheldon: Why don't you just take your clothes down to the river and beat them with a rock.

Raj: It's too bad he wasn't here for that hooker. She's exactly his type. A hooker.

Penny: Oh, I didn’t tell you? You’re banished from the Cheesecake Factory.
Sheldon: Why?
Penny: Well, you have three strikes. One, coming in. Two, sitting down. And three, I don’t like your attitude.

Raj: What's with him?
Leonard: Penny is keeping him up at night.
Howard: Me too. But probably in a different way.

Wolowitz: Leonard, how was your date?
Leonard: Bite me!