Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Penny: Sheldon, what did we say about being a nicer friend?
Leonard: Thank you.
Penny: Leonard, what did we say about being a gullible weeny?

Amy: I guess it must have been back when I was in the Girl Sprouts.
Bernadette: Girl Sprouts?
Amy: My mom made it up as an alternative to the Girl Scouts. She didn't want me selling cookies on some street corner like a whore.

Howard: So you can never take it (the sweater) off?
Leonard: No.
Raj: Not even to sleep?
Leonard: No.
Howard: So you're just an idiot?
Leonard: It's called proving a point.
Howard: Is the point you're an idiot?

Sheldon: I know why. You've come to me because you're my Obi-Wan.
Arthur: I'm not familiar with that. Is that an Internet?

Raj: (To Amy) If you were having Sheldon's baby, would you really want him in the room?
Penny: Yeah, if he's in the room when they're making the baby, I'll give you $10.

Howard: My arm is feeling numb. *Howard rubs his right arm*
Bernadette: That's the wrong arm for a heart-attack, doofus.
*Howard switches to his left arm*

Penny: No, mom. It's the same guy I've been going out with for the past two years. Yeah, the scientist. Well, it's complicated. He works with lasers and atomic magnets. No, I did not see it coming. No, we have not set a date. No, I am not pregnant. Yeah, this is a first for our family.

Sheldon: Sheldon Cooper does not get lucky.
Amy: You and me both, brother.

Amy: Do you have any idea how hard it is to laugh at a knock knock joke that starts "Knock Knock Knock, Amy. Knock Knock Knock, Amy. Knock Knock Knock, Amy"?

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?

Sheldon: I've got to find a way to stop this thing.
Leonard: Buddy, I don't think you can. Once it's out there, it's out there. This thing is like the science equivalent of a sex tape.
Sheldon: Frankly, I'd prefer a sex tape.
Leonard: You don't know what a sex tape is, do you?
Sheldon: No.

Bernadette: (Shouting from the bathroom) How many times do I have to tell you to replace the toilet paper when it's empty?
Howard: I'm in the middle of something.
Bernadette: So am I!

Bernadette: Aww, Raj did the dishes.
Howard: How do you know I didn't do them?
Bernadette: Because once when all the knives were dirty, you cut a bagel with your keys.

Penny: Howard, cow tipping - real or not?
Howard: I'm going to say not. That's just based on me trying to roll my mom over when she's snoring.