When a player knowingly uses a known or unknown map bug to gain an advantage or prevent a loss.
Examples include (but are not limited to):
Bypassing the wall limit in RCB by making unfinished walls.
Kings from AoE II games in stores making the player invincible, or other likewise inaccessible units preventing a player from losing a game.
Using provided assets to remove obstacles to not-yet-granted units in a store-oriented map (i.e. using a bombard tower to attack palisade walls blocking access to units not meant to be available to the player yet).
Hunt delete (AoM/AoT specific): Placing a building foundation over an opposing player's hunted animal, causing the animal to be deleted. (Screenshot and match link as minimum evidence)
Using a TC glitch to refund resources.