Leonard: Okay, is everyone clear on the plan?
Wolowitz: Yes. Koothrappali is going to wet himself, I'm going to throw up, Sheldon is going to run away, and you're going to die. Shall we synchronize our watches?

Leonard: What was the plan?
Penny: Um, waitress for six months and then become a movie star.
Leonard: Was there a Plan B?
Penny: TV star.

You know, I've given the matter some thought, and I think I'd be willing to be a house pet to a race of super-intelligent aliens.

Sheldon

Penny: No, I can't. Sheldon, honey, I don't want things to be weird between us.
Sheldon: Won't it also be 'weird' if I have to say hello to you every morning on my way to work and you're living in a refrigerator box and washing your hair with rainwater?

Penny: Wow, you've got a lot of money in there.
Sheldon: That's why it's guarded by snakes.

Raj: If you don't like this stuff, let's just go next door and build her a bear.
Sheldon: I told you before, bears are terrifying

Sheldon: If I were to give you this gift basket, based on that action alone, and no other data, infer and describe the hypothetical relationship that exists between us.
Employee: Excuse me?
Sheldon: Here. [gives woman gift basket] Now, are we friends, colleagues, lovers? Are you my grandmother?
Employee: I don't understand what you're talking about, and you're making me a little uncomfortable.
Wolowitz: See, sounds just like you and Penny. We'll take it.

Penny: Dave is not smarter than you, he's an idiot.
Leonard: Really? Why would you say that?
Penny: Because a smart guy takes the nude photos of his wife off his cell phone before he tries to take nude photos of his girlfriend.
Leonard: He tried to take nude photos of you?
Penny: That's what you took from that?

Leonard: Every time I try to talk to her about moving out she cries, and we have sex.
Raj: You're lucky. With me it's usually the other way around

Penny: You don't always have to go along with what the woman wants.
Leonard: Huh.
Penny: What?
Leonard: Nothing... just re-thinking my whole life

Sheldon: I need to know exactly what Leonard did to get you to put an emotional cap in his buttocks.
Penny: What?
Sheldon: Again, urban slang, in which I'm beginning to get remarkable fluency

Penny: Sheldon, what do you want?
Sheldon: I'm certain this will come as no surprise to you, but Leonard is failing in yet another relationship.
Penny: He's having problems with Stephanie?
Sheldon: She's sending virtual livestock to random men on the Internet

The Big Bang Theory Season 2 Quotes

Sheldon [to Kripke]: Also, I am given to understand that your mother is overweight.
Raj: Oh, snap.
Sheldon: Now of course, if that is the result of a glandular condition and not sloth and gluttony then I withdraw that comment.

How is "doable" anything but a compliment?

Wolowitz