Leonard: Hang on. Are you feeling insecure? Because that's my thing, and if you take it away, I don't know what I'm bringing to this relationship.

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: I have a lab full of coked up monkeys with nothing to lose.

Raj: I did the research. Tony the Tiger, Dig'em the Frog, Cap'n Crunch, Toucan Sam, Count Chocula, Trix the Rabbit, Snap, Crackle and Pop. Not one cereal mascot is a girl. It's a total breakfast sausage fest.
Leonard: Are we done with this?
Raj: Almost. Franken Berry, Boo Berry, Sugar Bear and the Honey Nut Cheerio bee, I believe his name is Buzz.

Sheldon: My father used to say that a woman is like an egg salad sandwich on a warm Texas day.
Alex: What?
Sheldon: Full of eggs and only appealing for a short time.