Found this out while getting boosted in ZF.
It seems like (atleast in ZF) if you reset the instance right when people jump in they will get disconnected and have problems log in for few minutes.
Not sure if it works in other instances but I see no reason why wouldnt it.
EDIT oh my god I typoed the topic name hard time. Crash your friends/partymates wow it was ment to be. Gonna sleep.