During the era of the Damnation hack on Starcraft, a coder created an anti-hack that would broadcast a message in the game, and if anyone was running the Damnation hack client, their units would become hostile to themselves, and they would destroy themselves. It was programmed by default to broadcast the message 5 minutes into a round, so I would wait until around the four minute mark, and say "I wonder if anyone is hacking..." then thirty seconds later see "WTF IS HAPPENING" or "OMGWTF" followed by a bunch of people leaving the game, even if they were my own teammates.
Couldn't help but trollface while I swept in and finished them off in the chaos, or won the game by having everyone leave.