I think I once electrocuted a fly that flew into the cooling vents on the top of my A500.
I think you're looking for the "Amazing things flies have done on your Amiga" thread. That must have been one hell of a fly. First of all, the fly would have to cram himself into a 2mm space to get into the A500 cooling vent, then find a way to electrocute himself by drilling into the plastic power connector and spreading his legs far apart to touch both connectors. Amazing.