Raj: But mummy, all the other guys are going to the North Pole.
Mrs. Koothrappali: I don't care what the other guys are doing. If the other guys jumped in the Bay of Bengal and tried to swim to Sri Lanka, would you follow them?

Howard: Dr. and Mrs. Koothrappali, namaste. I understand your concern, but if it'll make you feel any better, my mother is fine with me going. And this is a woman who kept a safety rail on my bed until I was 17.
Mrs Koothrappali: So, she has no problem with her son being eaten by a walrus?

Sheldon: Did you bring the dehydrated low-sodium soy sauce?
Leonard: Check.
Sheldon: Freeze-dried spicy mustard?
Leonard: Check.
Sheldon: Flash-frozen brown rice, not white?
Leonard: Uh, oh, sorry.
Sheldon: Not to worry. I hid it. Bazinga!

Penny: No, Fritz, I need you on my flank. No, I don't know German. Flankenzie, flankenzie!

Sheldon: Leonard, let me tell you something. Personal robots cannot get here soon enough.

Sheldon: In fact, I was briefly able to see the inside of my sister's guinea pig, Snowball, before he caught fire. It led to an interesting expression in our house, not a snowball's chance in a CAT scanner.

Barry Kripke: Are you crazy? This is a street fight. The street has no rules.

Sheldon: Just pick out anything? Maybe at the same time we can pick out a new suit for him without knowing his size, or pick out his career for him without knowing his attitude, or pick out a new breakfast cereal without knowing his fiber requirements or his feelings about little marshmallows.

Sheldon: Point of inquiry, why did you put your car key in the door lock?
Penny: Why? I'll tell you why. Because today I had an audition, it took me two hours to get there, I waited an hour for my turn, and before I could even start they told me I looked too Midwest for the part. Too Midwest? What the hell does that even mean?
Sheldon: Well, the American Midwest was mostly settled by Scandinavian and Germanic peoples who, well they have a characteristic facial bone structure...
Penny: I know what it means, Sheldon!

Sheldon: Excuse me. Thirty what, under thirty what, to watch what?
Raj: Thirty visionaries under thirty years of age to watch as they challenge the preconceptions of their field.
Sheldon: If I had a million guesses, I never would have gotten that.

Raj: Why did Howard leave you in the middle of the road anyway?
Sheldon: We had a difference of opinion.
Raj: Over what?
Sheldon: Whether or not he was trying to kill me. For the record, I maintain he was.

Leonard: Compromise. Watch Babylon 5.
Sheldon: In what sense is that a compromise?
Leonard: Well, five is partway between three... Never mind.

Penny: Yeah, Leonard mentioned you were a psychiatrist.
Beverly Hofstadter: Well, that is one of my degrees. My primary field is neuroscience.
Penny: Oh, well, I'm an actress.
Beverly Hofstadter: Why?
Penny: What do you mean why?
Beverly Hofstadter: Well, there are studies that suggest that many who go into the performing arts suffer from an external locus of identity.
Penny: Yeah, I don't know what that means.
Beverly Hofstadter: Well, it means you value yourself only as others value you, which is often the result of unmet childhood emotional needs.
Penny: Oh, well, I had a wonderful childhood.
Beverly Hofstadter: Tell me about it.

Leonard: You brought your husband to work, you know the rules. Meesa thinking yousa looking pretty sad now too, betcha, betcha.

Raj: It's hot in here. It must be Summer.
Summer Glau: That's cute.
Raj: Really? I just made it up. Have you seen Slumdog Millionaire?
Summer Glau: Oh, yeah, I loved it.
Raj: It's loosely based on my life.