Shallow passages in bases that allow pbp, bar and shipka users to have a constant bulletstorm pointed at you while you can't pass to try to actually kill someone, the glitch where someone with a pbp shoots you a couple of times when you're downed and you lose 20-30 hp, and the pull thing, because when you try to enter a door (this isn't for just pking obviously, but if you're streaking this is probably worse) you do the pull instead of grabbing so you can enter the room you want.