Raj: Can you even eat those things?
Leonard: If I take a Lactaid a half-hour before and some Pepto right after.
Raj: Sounds like a lot of work.
Leonard: Eh, I'm worth it.

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.

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: 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.

Amy: I gave you one job! Keep an eye on him. How hard is that?

Sheldon: Because there's only one of me, I'm more valuable.
Penny: Right.
Sheldon: Although, Amy's already taken me out of my package and played with me.

Amy: Why didn't you tell me?
Bernadette: We didn't want you to worry.
Amy: Should I worry?
Penny: No, come on, it's Sheldon. Nothing is gonna happen.
Amy: That's what you said to me when I started dating him. And then five years later, bingo-bango, something happened.