"How Not To Kill Your Business Partner."
"Teller almost never speaks while performing. There are exceptions such as when the audience is not aware of it; for example, he provided the voice of "Mofo the psychic gorilla" in their early Broadway show with the help of a radio microphone cupped in his hand. Teller's trademark silence originated during his youth, when he earned a living performing magic at college fraternity parties. He found that if he maintained silence throughout his act, spectators refrained from throwing beer and heckling him and focused more on his performance."