Penny: Maybe there's something in the book that will help.
Leonard: Worth a shot.
Penny: Okay. Let's see, let's see. "Biting other children"?
Leonard: Well, sometimes, but problem for another day.

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.

Penny: No, I've been reading Bernadette's parenting book. It's like the answer key to the Sheldon test.

Leonard: It's fine, I've been driving him for years. What's one more day?
Sheldon: Oh, and I've got a new car game we can play. It's called "What siren am I?"

Sheldon: All right, you ready for your next one? Just a warning, this one's a little annoying. (imitates a high-pitched siren)
Leonard: Let's take a little little break, I'm getting a headache.
Sheldon: Aw, right in the middle of our fun game.
Leonard: Yeah, weird.