Raj: Hey, Sheldon, guess what I've heard today.
Sheldon: I'd imagine you heard any number of things today. When you arrived at work, you undoubtedly heard: Hello, Raj; How are you, Raj; and given you're wearing a new sweater vest, you may have heard: "New Sweater Vest" and possible, though less likely "Nice Sweater Vest."

Sheldon: If you fail at this relationship, and history suggests you will, then we risk losing the medical officer that our landing party has always needed.
Leonard: What landing party?
Sheldon: You're Kirk, I'm Spock, Wolowitz is Scotty, Koothrappali is the guy who always gets killed. And now we've got McCoy.

Sheldon: My fists are not up because I'm milking a giant invisible cow.

Sheldon: Possible explanations for your symptoms are, in descending order of likelihood: hyperthyroidism, premature menopause, hosting an alien parasite, or, and I only include it for the sake of covering absolutely all bases, sexual arousal.
Amy: Where would I have picked up an alien parasite?

Sheldon: Your ovaries are squirting so much goofy juice into your brains you don't even know which way is up.

Sheldon: Don't worry. As you tertiary friend I'm prepared to step in and comfort you.
Howard: It's not really necessary.
Sheldon: Ah no. I'll finish making the tea while you narcissistically ramble on about whatever's troubling you.
Howard: Thanks.
Sheldon: That's what tertiary friends are for.

Sheldon: Amazing Spiderman, Ultimate Spiderman, Spectacular Spiderman, the Marvelous Adventures of Spiderman, Spiderman 2099?
Penny: Leonard?
Leonard: You know this can go on all night. Why don't you just come with us?
Penny: Ugh, that's what I was trying to avoid.
Sheldon: Oh, I forgot, Sensational Spiderman.

Sheldon: Now Fetch Me Will Wheaton! (SPEAKING KLINGON)
Wil Wheaton: Did that guy just say, "Revenge is a dish best served cold," in Klingon?
Stuart: I believe so.
Wil Wheaton: What is wrong with him?
Stuart: Everyone has a different theory.

Leonard: I don't think she's a whore.
Penny: Oh no, she's definitely a whore. She has no standards. ... Wait, where's Howard?
*Off screen:*
Wolowitz: Bonjour, mademoiselle. I understand you're new in town.
Sheldon: Oh, good God!

Penny: How do you not tear off his clothes and take him right here on this table?
Sheldon: If you do that I'll scream.

Leonard: The math is all there. It's not real.
Penny: Yes, it is.
Sheldon: Look, it's scientifically impossible for a person to tip a cow. Even you with your stocky build and lumberjack shoulders.

Sheldon: Amy pointed out you were only trying to manipulate me.
Amy: Which you also figured out by yourself.
Sheldon: Which I also figured out by myself!

Sheldon: Well, I've had a lot on my plate. We happen to live in a golden age of television.

Sheldon: Let's take this problem one step at a time. First, we need to decide whether we're calling it lee-ver or lev-er.
And the sooner we decide it's lee-ver, the sooner we can roll up our slee-ves - and not sle-ves - and get to work.
Leonard: We're going to be here for ee-ver.

Raj: So I was thinking, maybe we can come up with a name for the asteroid by combining our names.
Sheldon: That's a great idea. I've got it. We'll call it "Cooper".
Raj: How is that both our names?
Sheldon: "Koo" from Koothrappali and "per" from Cooper.
Raj: Yeah, so it's, like, "Kooper" with a "K"?
Sheldon: Nah, you're right, that's dumb.