Harry and Jim are two friends who are stand-up comics. Sometimes they do substitute work for each other. One day Harry calls Jim and says "Jim, I need you to cover for me at the Amnesiacs Hospital on Saturday. It's easy - I do the same routine every week, and it always brings the house down. I'll give you my script." So on Saturday, Jim goes to the Amnesiacs Hospital. He starts doing the routine, and at first everything's fine. Then halfway through someone stands up and yells "Hey wait a minute - I've heard that joke before!" Then someone else yells, "Yeah - this guy's a fraud!" Pandemonium breaks out, and Jim is driven from the stage by a hail of tomatoes. The next day Harry calls Jim and asks, "How'd it go?" "Not so good, Harry," says Jim, "Halfway through the routine they called me a fraud and booed me off the stage." "Don't worry about it," says Harry, "That happens every time!" Remark: This joke was devised by Davy Temperley, Eric Loeb, and me. The Amnesiacs hospital seems like a fertile source of jokes. This was our best attempt. Maybe somebody else can do better.
(From the "Rest" of RHF)