Penny: Hey, can you help me put some of the food out?
Leonard: Yeah. Let me finish packing this stuff up. You know how Sheldon is if he sees Christmas stuff lying around after New Year's.
Penny: Yeah, but he doesn't live here anymore.
Leonard: Well, he doesn't live at Walmart, but he still threw a tantrum when he saw Marshmallow Peeps after Easter. And that's the same man who complains you can't find Marshmallow Peeps after Easter.

Sheldon: I remember the song! It's called "Darlin'" by the Beach Boys! Oh, thank goodness! I'm not crazy! I don't have to take a pigeon as my bride!
Leonard: There goes our shot at him living on the roof.

Howard: Don't feel bad. Some day someone will be throwing out your work, too.
Leonard: That someone was Sheldon and the day was yesterday.

Professor Proton: Can I ask you a question?
Leonard: Yeah, sure.
Professor Proton: Why do you put up with Sheldon?
Leonard: Oh, you know because we're friends.
Professor Proton: Why?
Leonard: Wow, you ask really hard questions. Look, I know he can be aggravating, but what you have to remember is he's not doing it on purpose, it's just how he is. But he's also loyal and trustworthy and we have fun together.
Professor Proton: You know you're describing a dog?
Leonard: He did bite me once. But in his defense, I came up behind him while he was eating.
Professor Proton: They hate that.
Leonard: Sheldon is the smartest person I have met. He's a little broken and he needs me. And I guess I need him too.
Professor Proton: Why is that?
Leonard: Boy, you will not let this go, will you?

Amy: Well, uh, Howard and Bernadette had their baby.
Mary Cooper: (gasps) Oh, that's wonderful! Now, have they decided to raise it Jewish or regular?
Sheldon: Welcome to Texas.

Bernadette: Everyone's a better mom than me.
Raj: Oh, don't take it so personally, maybe your baby's just a jerk.

Mary Cooper: Sheldon, if you're trying to prove me wrong, the tighty-whities on your head ain't changing my mind.