Penny: Well, remember Kurt?
Leonard: Your ex-boyfriend?
Penny: Yeah. He got arrested for taking a whiz on a cop car.
Leonard: What?
Penny: He was drunk.
Leonard: I would hope so.

Penny: What about Howard and Raj? How did he become friends with them?
Leonard: I dunno. How do carbon atoms form a benzene ring? Proximity and valence electrons.
Penny: Sure, when you put it like that.

Howard: Behold the Mobile Omni-Directional Neutralization and Termination Eradicator! Or...
Leonard, Sheldon, Howard, Raj: Monte.

Sheldon: This is an auspicious moment, like Robert Oppenhiemer or Neil Armstrong, we need the appropriate words to mark this historic scientific event.
Rajesh: How about, die toaster, die!
Leonard: That'll do it!

Sheldon: What did the toaster oven ever do to you?
Leonard: What did I do to Jimmy Mullins in the third grade? He still punched me in the face with my own fists. Sorry, you little nerd. You were just in the wrong boys' room at the wrong time.

Leonard: Remember the day we first met and you asked me to go to your boyfriend's apartment to get your TV back? And he was 9 feet tall and he took my pants off and you said- What was that? What did you say? Oh, yes, you said you owed me one.
Penny: Oh, come on, that's not fair.
Leonard: I came home with no pants.

Leonard: Okay, don't take this as a criticism but you do have that over exposed to gamma radiation thing going on.
Penny: What?
Leonard: Usually your the easy going Bruce Banner but when you get angry you turn into (makes growling noise).
Penny: I turn into a bear?
Leonard: Gamma radiation, Bruce Banner; you didn't get the Incredible Hulk from that?

Penny: What?
Leonard: He said we should maybe enter you in the killer robot competition.

Leonard: Here's my home number, here's my cell, here's my office, here's my parents' number up in New Jersey, they always know how to reach me.

Leonard: What are you looking at? You've never seen a hypocrite before?

Penny: (To David) Usually the physicists I know are indoors-y and pale.
Leonard: I'm not indoors-y. I just wear the appropriate sun block because I don't take melanoma lightly.

Leonard: By the way, my leg is killing me. Thanks for asking.

Leonard: Okay, I have just one question for you. While I am perfectly happy with the way things are between us, you said that you didn't wanna go out with me because I was too smart for you. Well, news flash, lady: David Underhill is 10 times smarter than me. You'd have to drive a railroad spike into his head for me to beat him at checkers. Next to him, I'm one of those sign-language gorillas who knows how to ask for grapes. So my question is what's up with that?
Penny: (tearfully) Why are you yelling at me?
Leonard: Sorry, I'm sorry, I'm sorry. Never mind, we're cool.

Penny: Leonard, look. Sheldon's hugging me!
Leonard: It's a Saturnalia miracle.

Penny: David is not smarter than you, because a smart man would take the naked pictures of his wife off his phone before trying to take naked pictures of his girlfriend!
Leonard: He tried to take nude photos of you?
Penny: That's what you took from that?! The guy is married!
Leonard: Oh, that's terrible.
Penny: And you, if you're so fine with how the way things are between us then why are you so jealous?
Leonard: The important thing is he's married and that's terrible.
Penny: Nice save, genius.