To keep an idiot busy, write this on both sides of a sheet of paper: "Want to learn how to keep an idiot busy? Flip this over." This joke assumes that the supposed idiot keeps flipping the paper indefinitely, not realizing that he is the one being kept busy.
Variants of this joke have appeared on websites, animated images, T-shirts and computer applications. Additional steps may be added for a more convincing joke, but the basics are always the same; the unwitting participant is given an interminable task to complete with a hope of reward at the end.
A conceptually similar prank is the fool's errand, or snipe hunt. This prank, often done on newcomers as an initiation rite, has the victim looking for an object that doesn't or can't exist; puns or other wordplay are often involved. For example, someone may be told to go to a certain place to receive a "long weight." The person is never met at that place, instead he "receives" a long wait. Similarly, two people working in tandem may continually tell the victim to go to the other person for a meaningless task, such as sending him to repeatedly carry a piece of paper in an envelope.