Crossbooking in poker is a bet two players competing in the same event make between each other. It’s an agreement in which the losing player has to pay the winning player a percentage of the winner’s profits.
Crossbook Poker Example:
You and your friend signed up for a WSOP event, and agree to crossbook for 20%. If you both finish out of the money, the crossbook bet is a push. But, let’s say your friend busts, and you finish in the money and win $5,000. Based on the crossbook bet, your friend will have to pay you $1,000 on top of your tournament winnings.