check cop

noun

noun

Gambling, Games Slang An adhesive used by cheats to steal chips or coins from a stack using the palm of the hand.

Aside from that the professional gambler may use the "check cop" to diminish the pile of checks which the Opponent may have, or may use his own marked cards if he can manage to get them into the game1924, Science and Invention in Pictures, volume 12, page 146:

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