Penny: What if Sheldon had no choice but to be respectful?
Leonard: Is there a switch on the back of his neck we don't know about?

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: Hang on. Maybe there should be a "no insult" clause about me, too.
Sheldon: Do you still like cilantro?
Leonard: Yeah.
Sheldon: You're tying my hands here.

Howard: See, he's not wearing a tie.
Leonard: Well, he's a patent attorney. Maybe his tie is pending.

Leonard: Hold on, hold on. So the three of us do all the work and only end up with 25%? Patent Attorney: Dr. Hofstadter, this university has been paying your salaries for over ten years. Did you think we do that out of the goodness of our hearts?
Leonard: Well, until you just said that mean thing, kinda.