Howard: If you need liquid helium so bad, I know a guy who can get you some, if you don't ask too many questions.
Leonard: Who is he?
Sheldon: Where does he work?
Leonard: How does he get the helium?
Sheldon: How many questions are too many questions?
Howard: Maybe he's not for you.
Sheldon: Four questions. The answer's four.

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Leonard: What are we going to do?
Sheldon: Perform the experiment immediately.
Leonard: I'd love to, but we need liquid helium and our shipment's on back order for a month.
Sheldon: A month? What? Are you kidding me? That would have been a good time for you to soften the blow.
Leonard: That shirt brings out the blue in your eyes.
Sheldon: Thank you. Aren't you sweet?

Sheldon: He has glasses and I'm a know-it-all. We are not built for prison.

Sheldon: Uh, but this is violating university code.
Leonard: A little, but if I may quote Einstein, "The pursuit of science calls us to ignore the rules set by man"
Sheldon: Huh. All right, do it. Tell him we're in.
Leonard: Done.
Sheldon: I can't find that quote on the Internet. Did you make that up?
Leonard: Before I answer, may I just say your skin has never looked better.
Sheldon: Aren't you just made of sugar.