Great thread
As a player I would have wished you Godspeed...
A gaming buddy told me about a Vampire LARP he'd been playing at a friend's apartment. Unbeknowst to the players, an armed fugitive had been spotted fleeing down the street on which their apartment building was located. In the middle of the session, a knock is heard at the door. One of the players goes to answer it only to be confronted by a police officer in swat gear with an assault rifle in hand. The player, leaping to the conclusion that this is a surprise NPC in full costume, excitedly balls up his fist and raises it in the air (all combat actions in LARP are resolved with rock-paper-scissors contests) and declares his intention "I brutally punch you in the face!" The cop, who was canvasing the neighbourhood reacts instinctively to the perceived attack and whacks the player in the face with the but of his rifle, dropping him like a ton of bricks. Backup was called for and naturally some hurried explanations ensued.