Sheldon: Listen to that! 'Stomp, stomp, stomp.' It's Wolowitz and his stacked heels that fool no one.

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: What's funny about Cylon toast?

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

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

Sheldon: The entire institution of gift giving makes no sense. Let's say that I go out and I spend 50 dollars on you. It's a laborious activity because I have to imagine what you need whereas you know what you need. Now I could simplify things, just give you the 50 dollars directly and then you could give me 50 dollars on my birthday and so on, until one of us dies leaving the other one old and 50 dollars richer. And I ask you is, it worth it?

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: 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.

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: 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: 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: Are you drinking whiskey?
Sheldon: Indeed. If I'm to participate in the social convention that is the "stag night," then I must embrace all its components, including tobacco, swear words and, yes, alcohol. Jeepers, that's yucky!