Items required for the game include three small opaque containers, a token, and a flat surface. The game begins with the perpetrator, often called a con-artist, placing the token under one of the three containers, then quickly sliding the containers around until the container that holds the token is uncertain. The object of the game from the mark's perspective is to guess which container holds the token. To keep the mark from hearing the token rattle around inside the containers, the perpetrator may use a soft item such as a ball made of cloth, sponge, or rubber.
The secret of the game lies in the perpetrator's ability to perform sleight of hand with the token while shuffling the containers. He can thus ensure that the mark will lose no matter which container he picks, then slip the token into a different one.
Often, an accomplice to the con-artist will play the game to build the mark's confidence in the possibility that the game is winnable. In reality, the con-artist makes sure that the token is under the pre-determined container when the accomplice is playing.
Neelix and Tom Paris unsuccessfully used this scam on The Doctor, in an attempt to prove their deceptive instincts had not dulled with time, after they were conned by Dala and Mobar. (VOY: "Live Fast and Prosper")