Pile jumping means attacking a player who has just killed someone else in a player-killing area. In other words, it's attempting to kill an already weakened opponent who may be busy looking at their loot from a previous kill. Pile jumping can be considered as dishonorable since the player being jumped may have been able to easily take out their jumper if they were ready. The abbreviaton PJing can also mean player jumping, which is attacking a player whose opponent is not dead yet. The word pile refers to multiple players attacking another.