What's up, Doc?". The phrase was written by director Tex Avery for his first Bugs Bunny short. Avery explained later that it was a common expression in his native Texas and that he did not think much of the phrase. When the short was first screened in theaters, the "What's up, Doc?" scene generated a tremendously positive audience reaction. As a result, the scene became a recurring element in subsequent films and cartoons.

The phrase was sometimes modified for a situation. For example, Bugs says "What's up, dogs?" to the antagonists in A Hare Grows in Manhattan, and "What's up, prune-face?" to the aged Elmer in The Old Grey Hare. He might also greet Daffy with "What's up, Duck?"