From MagicPedia
Three-Card Monte, also known as the Three-card marney, Three-card trick, Three-card shuffle, Triplets, Follow the lady, Find the lady, or Follow the Bee is a confidence game in which the victim, or mark, is tricked into betting a sum of money that they can find the money card, for example the queen of spades, among three face-down playing cards. In its full form, the three-card Monte is an example of a classic short con in which the outside man pretends to conspire with the mark to cheat the inside man, while in fact conspiring with the inside man to cheat the mark.
It should be noted that even if the game is played without the usual sleight of hand, it is unfair to the players, as the payout is invariably even money, whereas the true odds are 2/1.
This confidence trick has a great deal in common with the Shell Game
