I was swapping some exhausts over on a mate's car on Saturday, and had to Dremel off a particularly stuck bolt. It was all going fine until the entire head of the Dremel, complete with cutting disc still rotating at 10,000RPM, flung itself off the main unit and caught me across my knuckles.
It wasn't until I looked at the tiny nick on one knuckle (literally only just broke the skin) that I kinda stopped and realised just how incredibly fortunate I'd been to not lose a finger completely. That would've put a downer on the day somewhat I suspect.