What is "hand-in-cap"

Hand-in-cap is an old English trading game and the term itself is the origin of the modern word " handicap".

In this game, two players want to trade possessions. An umpire decides whether the items have the same value, and if not, what the difference is. Both players and the umpire then put some forfeit money in a cap. The players put their hands in the cap, and then remove them either open, to signal agreement with the valuation, or closed, to signal disagreement. If both players agree, the difference in valuation is paid, the items are traded, and the umpire collects the forfeit. If both players disagree, the items are not traded, and the umpire collects the forfeit. If one player agrees and the other does not, the items are not traded, and the player who agreed to the valuation collects the forfeit.