Zack: Are you guys fighting?
Penny: Yeah.
Leonard: No.
Zack: Are you fighting about whether or not you're fighting? 'Cause I've had that fight before. Turns out we were, and I lost.

Zack: One question. How can you be sure it won't blow up?
Leonard: The laser?
Zack: The moon.

Zack: Whoa, you dated Penny?
Leonard: She didn't tell you?
Zack: She told me she dated a guy named Leonard. Who would have thought it was you?
Leonard: Who else would it be?
Zack: I don't know. Somebody bigger and- Yeah, sure. Why not you?

Leonard: Don't worry about the moon. We, we set our laser to stun.
Zack: Smart.
Leonard: Now, we'll be able to see the beam when it leaves, but it won't be strong enough when it comes back to be seen by the naked eye.
Zack: (chuckling) Naked.

Sheldon: Oh, Stuart, good. I was wondering, will you be accepting Bitcoin?
Stuart: Well, I don't know what that is, but it's got "coin" in it, and my cash register doesn't, so yeah.

Mrs. Wolowitz: Howard, what's going on?! Are you boys roughhousing?!
Howard: No, we're not roughhousing! We're scientists! Scientists don't roughhouse!
Mrs. Wolowitz: Excuse me, Mr. Grown-up!

Mrs. Wolowitz: Howard, I made cookies for you and your little friends!
Howard: They're not my little friends, and we don't want cookies!
Leonard: Actually, a cookie sounds good.
Howard: All right, we'll have cookies! Thank you very much!