Anything involving the AI. Seriously, I was on Versus a few minutes ago, francis' player ragequit. I ran into the stairs at mercy hospital to get hunted with him standing behind me. It took the fucking thing 40 seconds to realise my nipples were being pulled off and finally hit the hunter off.
Some other guys are real dolts too, again on No Mercy I was a smoker and was trying to get my hunters up to the roof so we could ambush the survivors. They spawned right by the elevator shaft, the boomer, however, came up.