Sheldon: A fear of heights is illogical. A fear of falling, on the other hand, is prudent and evolutionary.

Wolowitz: *After he fixed Sheldon's algorithm* Gee, why can't Sheldon get a friend?

Raj: Ooo.
Penny: What's the matter, Lassie? Did Timmy fall down the well?

Sheldon: In Papua New Guinea, there's a tribe when a hunter flaunts his success to the rest of the village, they kill him and drive away evil spirits with a drum made of his skin. Superstitious nonsense, of course, but one can see their point.

Howard: Easy. Instead of saying; 'No we don't wanna go on an NSF expedition,' say; 'No we don't wanna spend three months stuck in a cabin in the Arctic Circle with an anal nutbag!'

Sheldon: When you understand the laws of physics, Penny, anything is possible. And may I add, "Mwah, ha, ha."

Sheldon: This is banana bread.
Penny: This is a door knob.

Sheldon: You know, I'm given to understand that there's an entire city in Nevada devoted specifically to help people like Howard forget their problems. They replace them with new problems such as alcoholism, gambling addiction and sexually transmitted diseases.

Hooker: What's your name?
Raj: Rajesh Ramayan Koothrappali.
Hooker: Hello Rajesh Ram...Hello Rajesh.

Leonard: How could you just sit there and let them spy on me?
Sheldon: They were very smart. They used my complete lack of interest in what you are doing.

Wolowitz: As delicious as the appetizer may be, sooner or later we will have to succumb and eat the entree while its still ... hot.

Leonard: Oh, hey, Stuart. This is Penny. She's looking for some comic books.
Stuart: Oh, really? Blink twice if you're here against your will.

Raj: What's with him?
Leonard: Penny is keeping him up at night.
Howard: Me too. But probably in a different way.

Sheldon: Everyone at the university knows I eat breakfast at 8:00 and move my bowels at 8:20.
Leonard: Yes, how did we live before Twitter?

Raj: It's too bad he wasn't here for that hooker. She's exactly his type. A hooker.