Leonard: Look, Sheldon, you were a jerk to Bert, and he walked away from you. So I feel like there's a lot he could teach me.

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.

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: They're very different. Physics answers the question: what is the nature of the universe? Geology answers the question: you know, what'd I just trip over?

Sheldon: I've been modeling different types of dark matter and the traces they would leave on the zircon inside your meteorite.
Bert: What's this one here?
Sheldon: That's actually a dark matter model of my own creation. I call it the Cooper Boson.
Bert: Cool. I got to name a rock once. I named it Moderately Sedimented Shale. Guess I kind of pooped the bed on that one.

Amy: What's going on?
Sheldon: What if there was something I wanted to do, but I was worried other people would think less of me?
Amy: Is that other person me, and does it happen in the bedroom, in which case I think I'm cool with it?
Sheldon: No. It's about working with Bert on - You know what? I'm not even gonna say it. I am just gonna say the letter it starts with and -"ology". G-- Oh, no, that's not gonna work.