Ace Up the Sleeve

A phrase coined to describe an Ace card that is withdrawn from the deck by a cheat using sleight of hand (possibly into adjacent clothing) to be re-introduced later at a favourable moment for the cheater.

Usage: Describing the situation in which a cheater has withdrawn an ace from the deck to be introduced into the game later, or, more generally, has taken some unfair advantage. The phrase passed into general usage to describe the situation in which someone is hiding some probably unfair advantage.