A common spare. The Miss Congeniality of the Bowling Pageant.

Wolowitz: Why is Leonard being a giant douche? That is, assuming, of course that giant douches are possible.
Sheldon: Of course they are -- Leonard's being one.

Wolowitz: Okay forgot giant ants. How about giant rabbits?
Raj: Big or small, I don't like rabbits. They always look like they're about to say something, but they never do.
Sheldon: Rabbits do have a respiratory system that would support great size. And as a side note, they are one of the few animals whose scrotum is on the front of the penis.
Raj: Maybe that's what they want to talk about.

Didn't work. This alcohol is defective.

A neutron walks into a bar and asks, "How much for a drink?" The bartender says, "For you? No charge."

Why did the chicken cross the mobius strip? To get to the same side.

Sheldon: I recently had a dream that I was giant, but everything around me was to scale, so it all looked normal.
Leonard: How did you know you were a giant if everything was to scale?
Sheldon: I was wearing size "a million" pants.

Raj: These methods come from the ancient gurus of India, and have helped me conquer my own fears.
Sheldon: And yet you can't speak to women.
Raj: True, but thanks to meditation, I am able to stay in the same room with them without urinating.

Penny: So what do you say, Sheldon, are we your X-Men?
Sheldon: No, the X-Men were named for the "X" in "Charles Xavier." Since I am Sheldon Cooper, you will be my "C-Men."

Leonard: We think we can help you with your stage fright.
Sheldon: Oh, I doubt that. I haven't figured out a way, and I'm much smarter than all of you.
Penny: Yes, buy you're not smaller than all of us put together.
Sheldon: I'm sorry, that is what I meant.

Penny: I once got a pretty big honor in high school, and I was terrified about appearing in front of a big crowd, but I went through with it, and you know what? The world looked pretty darn good sitting on a haystack in the back of a Ford F-150 as a member of the corn queen's court.
Sheldon: Thank you. I'll bear that in mind if I'm ever nomianted for the hillbilly peace prize.

Leonard: What, to you, is a large crowd?
Sheldon: Any group big enough to trample me to death. General rule of thumb is 36 adults or 70 children.

TBBT Quotes

Stephen Hawking: You made an arithmetic mistake on page two. It was quite a boner.
Sheldon: No, no ... that can't be right. I-I don't make arithmetic mistakes.
Stephen Hawking: Are you saying I do?
Sheldon: Oh, no, no, no, of course not. It's just, I was thinking.... Oh, gosh, golly, I made a boo-boo and I gave it to Stephen Hawking.
Stephen Hawking: Great, another fainter.

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.