I had a spectacular one during the weekend where I killed an enemy, a teammate and the damage reflection killed me. All one bullet. Two headshots and an aneurysm. On the 2nd to last point of Checkpoint with only the two of us on the server.
He apologised and we laughed, but whoever conceived the damage reflection system was an idiot. Whoever thought we'd love it so much we wouldn't want a server command to disable it probably makes friends with plants.