Raj: Why do you put six sugars in your coffee?
Leonard: Because the cafeteria doesn't offer little packets of methamphetamine.

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.

Sheldon: I would have been here sooner but the bus kept stopping for other people to get on it.

Leonard: You call that a glow stick? *Pulls out a Lightsaber* That is a glow stick!

Penny: Sheldon, that's not what girlfriends are for. Although you don't use them for what they're for, so what do I know?