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.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

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: 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.