Payback is a special status effect that appears in Paper Mario: The Thousand-Year Door.
When someone has Payback in effect, attacks will be countered. This mainly includes direct attacks. There are a few ways one can get the Payback status. The best way is to use a Spite Pouch. Admiral Bobbery's Hold Fast special move gives him the Payback status as well. Sir Grodus is a notable boss that can give himself the Payback status while Poison Puffs are some of the only enemies in the game that can give themselves Payback.