Sheldon: Yes, this is doctor Sheldon Cooper. Is this the Zack Johnson that used to have coitus with my neighbour Penny? Sorry to bother you. (to different person) Hello I'm looking for a Zack Johnson that used to have coitus with my neighbour Penny. Coitus. It means intercourse and I have a feeling I'm speaking to the right Zack.

Sheldon: Unlikely, but make your case. Keeping in mind your critical attitude is ruining our Saturday night together, and I'm not above minimizing your window.

Sheldon: It's hard to say no to Yoo-hoo. The name literally beckons.

Sheldon: I love astro-physics. It's like looking at the universe naked.

Sheldon: My hands are magic.

Sheldon: Tell Mom that I currently weigh 165 pounds and that I'm having regular bowel movements.

Sheldon: Explain to me an organizational system where a tray of flatware on a couch is valid. I'm just inferring that this is a couch, because the evidence suggests the coffee table's having a tiny garage sale.

Leonard: Come on, you need a four-person team. We're four people
Sheldon: By that reasoning we should also play bridge, hold up a huppah and enter the Olympic bobsled competition.

Penny: You'll never guess what just happened.
Leonard: Oh, I give up.
Sheldon: I don't guess. As a scientist, I reach conclusions based on observations and experimentation. Although it occurs to me, you may have been employing a rhetorical device rendering my response moot.

Penny: I'm so sorry. I really thought if you guys went instead of me, he wouldn't be such an ass.
Leonard: No, it was a valid hypothesis.
Sheldon: "Was a valid hypo-" . What is happening to you?

Sheldon: Can't we just go to Big Boy? They only have one burger: the Big Boy.
Penny: The Barbecue Burger is like the Big Boy.
Sheldon: Excuse me, in a world that already includes a Big Boy, why would I settle for something that's like a Big Boy?

Sheldon: I will form my own team and will destroy the molecular bonds that hold your matter together, and reduce the resulting particular chaos to tears.
Leonard: Thanks for the heads up.

Penny: Aww, that's great. You're going to be an uncle. Uncle Sheldon.
Sheldon: No, I will be Uncle Dr. Cooper.

Amy: Listen, you and I are gonna be sharing a bed. You know, this is uncharted territory for both of us. How are you feeling about that?
Sheldon: Oh, excited, concerned, a little scared. All the same emotions I feel in line at Space Mountain.

Raj: Yeah, okay, whatever it takes to keep you busy for a few hours.
Sheldon: Found one.
Raj: No, you didn't. There are millions of data points there.
Sheldon: But, look, an optical transient.
Raj: Yeah, maybe that is something. How did you find that?
Sheldon: It wasn't difficult. You know how when you see prime numbers, they appear red, but when they're twin primes, they're pink and smell like gasoline?
Raj: No.
Sheldon: Oh. I guess I'm a special boy. You know, sometimes when a boy is special, he gets a Fudgsicle. Which, by the way, tastes like the speed of light.