Raj: No, no, no, no, that rate is much too low for what you'd expect from this collision. Do you understand we're taking about dark matter colliding in outer space?
Sheldon: Yes, of course I understand, and who are you to tell me about outer space?
Raj: Well, I am the astrophysicist! Astro means space!
Sheldon: Astro means star.
Raj: Okay, let me just tell you, if we were having this argument in my native language, I'd be kicking your butt!
Sheldon: English is your native language!

Sheldon: Yes, since their relationship became carnal, Penny has updated his designated term of endearment, distinguishing him from those she calls "sweetie," usually as an attempt to soften a thinly-veiled insult.
Penny: You're boring people, sweetie.
Sheldon: Although sometimes, she omits the veil entirely.

Leonard: I've always been a little confused abut this -- why don't Hindus eat beef?
Raj: We believe cows are gods.
Sheldon: Not technically. In Hinduism cattle are thought to be like gods.
Raj: Do not tell me about my own culture Sheldon! In the mood I'm in I'll take you out, I swear to cow!

Interesting. Sex works even better than chocolate to modify behavior. I wonder if anyone else has stumbled onto that

Sheldon: Leonard, you can't train my girlfriend like a lab rat
Leonard: Actually, it turns out I can
Sheldon: Well you shouldn't

Penny: I give up, he's impossible
Sheldon: I can't be impossible, I exist. I believe what you meant to say is, "I give up, he's improbable."

Penny: I'll tell you what, next french toast day, I'll make you oatmeal
Sheldon: Good lord, are you still gonna be here next french toast day?

Raj: I don't like bugs, okay? They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Raj: What happened?
Sheldon: Obviously another carnal fiasco with the 'Shiksee' goddess.
Howard: Shiksa. Shik-Sa.
Sheldon: Forgive me. Yiddish was not spoken in East Texas. And if it was, it wasn't spoken for long.

Howard, you know me to be a very smart man. Don't you think that if I were wrong, I'd know it?

Penny: You know, I do understand what you're going through.
Sheldon: Really? Did you just have the Nobel Prize in Waitressing stolen from you?

Hello, Penny. I realize that you're currently at the mercy of your primitive biological urges, but as you have an entire lifetime of poor decisions ahead of you, may I interrupt this one

TBBT Quotes

James Earl Jones: Why don't you and your friends come to Comic-Con with me?
Sheldon: Really?
James Earl Jones: Of course. And San Diego is right across the border from my favorite city on Earth, Tijuana.... where I'm taking you every night!
Sheldon: Ay-yi-yi.
James Earl Jones: Ay-yi-yi. Bang. Bang.

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.