Chip dumping in poker describes a pattern of behavior where two or more players work together to move chips between their stacks, ensuring they all stay in the game at the expense of other players in a tournament.
One blatant example of chip dumping would be a player betting big on two streets, checking to their opponent on the river, and folding to their tiny all-in. Of course, chip dumping can be done in a way that is much harder to detect.
As mentioned, the point of this practice is to ensure all players working together last for as long as possible in the tournament, which gives colluding players an unfair advantage over the rest of the field. Because of this, chip dumping is defined as cheating and, when caught, can lead to harsh penalties, including a disqualification from the tournament.