Penny: I grew up on a farm. From what I heard, they're either having sex or Howard's caught in a milking machine.

Mrs. Koothrappali: What are we suppose to tell Lalita's parents?
Dr. Koothrappali: I play golf with her father, I won't be able to look at him.
Raj: Why don't you keep your eye on the ball, Papa?

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.

Sheldon: I'm a superior genetic mutation, an improvement on the existing mediocre stock.
Missy: And what do you mean "mediocre stock"?!
Sheldon: That would be you.

Leonard: How long is he going to stay here?
Sheldon: He's a homeless drug addict, Leonard. Where's he going to go? Boy, you have a lot to learn about lying.

Leslie: Come for the breasts, stay for the brains!

Wolowitz: I am the sword master!

Penny: Well what happened?
Mary Cooper: The poor boy had a fit. Locked himself in his room and built a sonic death ray.
Leonard: A death ray?
Mary Cooper: Well, that's what he called it. It didn't even slow down the neighbor kids. It pissed our dog off to no end.

Sheldon: If she were to log on to www.socalphysicsgroup.org/activities/other, click on upcoming events, scroll down to seminars, download the PDF schedule, and look for the seminar on molecular positroneum, well then, bippity boppity boo, our pants are metaphorically on fire.
*Leonard shuts the door.*
Sheldon: Well, sir, my trousers will not be igniting today.

Penny: What I'm saying is, Leonard might be different in a good way. And obviously, my usual choices have not worked out so well.
Sheldon: Your last choice worked out for Koothrappali. He got a free iPod.

Dr. Gablehauser: Okay, well, speaking of spreads, we're having a small welcoming party this afternoon for Mr. Kim who's agreed to join us here at the university.
Sheldon: Of course he has. The Oracle told us little Neo was the one. You can see the matrix, can't you?

Leonard: Why don't you just tell people you're a zebra?
Sheldon: Why don't you just tell people you're one of the seven dwarves?
Leonard: Because I'm Frodo.
Sheldon: Yes, well, I'm the Doppler effect.

Howard: Ooh, more details about the new Star Trek film! There is going to be a scene depicting Spock's birth.
Raj: I'd be more interested in a scene depicting Spock's conception.

Howard: Sheldon, there's a diploma in my office that says I have masters in engineering.
Sheldon: And you also have a note from your mother that says "I love you, Bubula" but neither of those is a cogent argument for titanium over nano-tubes.

Raj: (Mocking Howard) Ooh! Look at me, I don't have a foreskin!