Foul play can vary from two players boosting (continuously killing each other to increase points) to clan members joining a game and teaming up to kill other players. I believe that this ruins the Free-for-all experience that rumble is supposed to have and makes it extremely hard to enjoy. I've had this happen to me on more than one occasion and wanted to see if others are having the same experience. The main way to fix this issue is to get rid of the ability for fire teams to join rumble matches. Making it significantly harder to team up within the game mode.