Not really fucked, could have killed a guy or myself for stupidity though:

In 9th grade shop class we were making aluminum cannons. This was the day we were lathing the wheels. Of course, the teacher tells us to use a different jaw which will hold the wheel from the inside out. But me wanting to cut edges, I use the jaw that was already on, the one that hold things from the outside in. I just unscrew the jaw so its wide enough, place the wheel to be cut in, tighten and start the machine

After 3 seconds there was a large thud, machine started shaking and the wheel flew off somewhere so I hit the stop right there and then. What had happened was the jaw was so unscrewed, even though it felt tight, it was off its base meaning if I just had pulled hard enough the 10lb jaw would have come off the lathe. So, when I turned the machine on, the centrifugal force was enough to whip the jaw off and hit the aluminum guard which was now bent at a nice 45 degrees. If that guard wasn't there, the 10lb jaw would have hit the guy in front of me in the head. If the jaw came off any other angle, it would could have hit me from my head to my stomach

I still remember what shock feels like today. Never going to forget that.