Leonard: "How are you with pets?" Well, I did take care of Sheldon for 15 years, and he only bit me twice.

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.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

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.

Amy: Hey. Wait a minute, what about us? I mean, we're married now. Maybe we want to buy the house next door.
Sheldon: Well, Amy, we can't move. I'd have to change all the tags in my underwear.
Amy: You can buy new ones.
Sheldon: New house, new underwear. What am I, in the Witness Protection Program?

Amy: What the hell, Penny?!
Penny: I'm gonna need more than that.
Amy: You're not having kids? How could you do this to me?
Penny: How is it any of your business?
Amy: Because your kids were supposed to be friends with my kids. Who's gonna be friends with them now?
Penny: They will find other friends.
Amy: Oh, sure, 'cause Sheldon's DNA plus my DNA equals a kid who knows how to make friends. Grow up!

Sheldon: You're awfully quiet.
Leonard: Sorry.
Sheldon: No, I like it.
Leonard: Got a lot on my mind.
Sheldon: Would you like to talk about it?
Leonard: Not really.
Sheldon: Grape Nuts for breakfast, quiet car ride, things are really breaking my way today.