I was helping a friend put up some walls in his basement and he was using a nail gun. He was having problems with the compressor. He partially disassembled the knob on the top that lets you adjust the pressure to see if he could figure out the problem. He put it back together and picked up the gun to see if it was working better. The adjustment knob then exploded and shot straight up into the ceiling… right where his face had been just moments before.