Howard: It's hot in here, it must be Summer.

Leonard: We had a vote. Three of us voted for airplane. Sheldon voted for train, so we're taking the train.
Sheldon: Don't say it like that, Leonard. Say it like, "We're taking the train!"

Sheldon: I'd like to have a talk about relationships.
Raj: You were supposed to have the talk with him.

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.

Raj: I'm curious, what part of America is that accent from?

Mrs. Wolowitz: Want me to get you a popsicle?
Howard: Cherry, please!
Mrs. Wolowitz: I ate the cherry. All that's left is green.
Howard: You make me wanna kill myself!

Penny: Normally, I can just ignore you. I mean, I get it. You're a little peculiar. Like Sheldon.
Sheldon: Excuse me, Penny, but in this room, you're the one who's peculiar.

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.

Raj: Okay, what shall be the first to taste the wrath of MONTE?
Leonard: Maybe we should start small.
Raj: Okay, oh, perhaps today is the day we finally find out what's inside the Magic 8 Ball.
Sheldon: Did it when I was 4. It's an icosahedral die floating in tinted blue water.
Raj: Man, call spoiler alert before you say things like that.

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.

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

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.

Howard: Gather around, kids. It's time for Sheldon's beloved Christmas special.
Sheldon: In the pre-Christian era, as the winter solstice approached and the plants died, pagans brought evergreen boughs into their homes as an act of sympathetic magic, intended to guard the life essences of the plants until spring. This custom was later appropriated by Northern Europeans and eventually it becomes the so-called Christmas tree.
Howard: And that, Charlie Brown, is what boredom is all about.

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

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.