When a Fantasy Football owner drops a player, he enters a pool of free agent talent and can be acquired by another owner. This system is exploitable by colluding owners who are intent on passing strong players from team to team. They simply select a specific time for one owner to dump a player and, while the other owners in the league are unaware, the second colluder swoops in and claims the stud. While this may seem like abiding by the rules of the league, it is a blatant form of cheating.
Most Fantasy Football leagues use a waiver wire to give every owner a fair chance at picking up discarded players. Although the waiver wire is designed as a way to prevent collusion between owners, it ironically provides a small window for unscrupulous owners to exploit this rule. When an owner has first rights to any waived player, there is virtually no way to prevent a colluder from passing them a stud via the rules of the wire. All the cheater has to do is drop the player and let his or her conspirator pick him up.