thimblerig

The game of thimblerig seems innocent enough. The thimblerigger places a little ball, pea, or other small object under one of three thimbles or cups. He or she deftly scoots the cups around on a table, then asks the player to bet on which one hides the object. But thimbleriggers are masters of sleight of hand and can move and manipulate the object unfairly—so the guileless player doesn't stand a chance of winning. (The poor bettor is probably unaware that rig has meant "to manipulate or control usually by deceptive or dishonest means" since the 1800s.) When the same sham is played with nutshells, it's called a shell game, and there's a related game played with cards known as three-card monte.