Leonard: You speak English really well.
Dennis: So do you... except for your tendency to end sentences with prepositions.
Leonard: What are you talking about?
Dennis: That.
Sheldon: He's not wrong

The local cuisine was a little more sausage-based than I'm used to, and the result was an internal blitzkrieg, with my lower intestine playing the part of Czechoslovakia

Sheldon [on studying in Germany]

[at The Cheesecake Factory]
Penny: Why didn't you just have soup at home?
Sheldon: Penny, I have an IQ of 187. Don't you imagine if there were a way for me to have soup at home, I would have thought of it?
Penny: You can have soup delivered.
Sheldon: I did not think of that

Leonard: Sheldon, don't you think you're overreacting?
Sheldon: When I'm lying comatose in a hospital, relying on inferior minds to cure me, these Jell-O cultures and my accompanying notes will give them a fighting chance

Sheldon: Checkmate.
Leonard: Argh, again?
Sheldon: Obviously you're not well-suited for three-dimensional chess. Perhaps three-dimensional Candyland would be your speed

Leonard: Alright, get some rest and drink plenty of fluids.
Sheldon: What else would I drink? Solids? Gases? Ionized plasma?
Leonard: Drink whatever you want

Sheldon: Anyway, the housekeeper in the faculty residence didn't speak any English. When I finaly managed to convince her I was sick, she said, "Möchtest du eine Darmspülung?"
Penny: What does that mean?
Sheldon: Based on what happened next, I assume it means, "Would you like an enema?"

If influenza was only contagious after symptoms appear, it would have died out thousands of years ago. Somewhere between tool using and cave painting, Homo habilis would have figured out to kill the guy with the runny nose

Sheldon

Leonard: We're going to Long Beach?
Sheldon: No, of course not. There's no Cousin Leo; there's no intervention. Focus, Leonard.
Leonard: Oh, come on.
Sheldon: We just leave the house on Friday night, and we return in the wee hours, emotionally wrung out from the work of convincing Leo to go back into rehab.
Leonard: So, he goes back into rehab?
Sheldon: Yes, but he can relapse if Penny ever invites us to hear her sing again

Every family in America has a relative holed up in a garage somewhere huffing paint thinner

Penny

Leonard: Sheldon, are you worried about your safety?
Sheldon: No, I imagine if you were going to kill me, you'd have done it a long time ago.
Leonard: That's very true

Leonard: Penny, say hello to Leo.
Penny: Hi, Leo. How are you feeling?
"Leo": Have you ever woken up in a flea-bag motel, covered in your own vomit, next to a transsexual prostitute?
Penny: No.
"Leo": Then don't ask me how I'm feeling.

The Big Bang Theory Season 1 Quotes

Leonard: We need to widen our circle.
Sheldon: I have a very wide circle. I have 212 friends on MySpace.
Leonard: Yes, and you've never met one of them.
Sheldon: That's the beauty of it

Leonard: At least I didn't have to invent 26 dimensions just to make the math come out.
Sheldon: I didn't invent them, they are there!
Leonard: In what universe?
Sheldon: In all of them, that's the point