Penny: He's such an angel when he's asleep.
Leonard: Yeah. Shame he has to wake up.
Penny: I think we can do it.
Leonard: Smother Sheldon in his sleep? Wouldn't that be wrong?

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.

Raj: Hey, Leonard?
Leonard: Yeah?
Raj: I haven't had sex in a year.
Leonard: Where are you going with this, Raj?
Raj: Don't flatter yourself, dude.

Leonard: Hey, where've you been?
Sheldon: I was talking with Penny.
Howard: What's wrong with you? You can't hang out with your roommate's ex. That's totally uncool.
Leonard: No, it's fine. I don't care. I'm over it.
Raj: Yeah, he's over it; that's why he's been whining all day about trying to invent that memory-wiper gizmo from Men in Black.
Sheldon: Is he making any progress? Because I'd like to erase Ben Affleck as Daredevil.
Howard: So would Ben Affleck.

Penny: So, how've you been?
Sheldon: Well, my existence is a continuum, so I've been what I am at each point in the implied time period.