Penny: No, it does matter. Okay? You were right. It was Halloween. I was dressed as a cat, you were a hobbit. It was right there on that couch.
Leonard: Why didn't you just say that?
Penny: Because I always hated that was our first kiss. I was drunk, and I was still with Kurt, and I was using you to make myself feel better. I just wanted our first kiss to mean something. That's why I said it was the one on your birthday.
Leonard: I like that. We'll make that our official first kiss.

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: Hey, why aren't you in your costume?
Sheldon: I just didn't feel like it.
Amy: You get that I'm wearing a corset because of you, not because I'm tired of breathing?

Leonard: Oh, my God, you look amazing.
Raj: I find you guilty of murder, because you are killing it.
Howard: (imitating Sheldon) Well, technically, the Supreme Court wouldn't determine a defendant's guilt or innocence in a criminal matter. They could only reverse or revamp a jury's conviction based on a constitutional or statutory issue.

Howard: You're sitting in my spot.
Sheldon: You don't have a spot. What is wrong with you today?
Raj: Maybe he's cranky because he's off his bathroom schedule.