Sheldon: What if the helium dealer rats us out? What if Kripke asks where we got it? What if the university checks my family tree and finds out I don't have an Uncle Harvey?
Leonard: The dealer doesn't care, Kripke has no authority over us, and you being related to a metal container would explain a lot.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Leonard: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

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.