OK, this didn't happen to me, but I was a witness!
One day, at about three years of age, I was watching my Dad mow the lawn. He was using an old Toro. You know the type - a gas engine, pull start, side-bagging push mower. The grass was a bit damp and soon clogged the chute. Dad decided that it was a good idea to remove the bag and clear the blockage without turning off the mower. Even at that age, I told him not to do it, but he was never one to take good advice from anyone.
Predictable results ensued (I'll never forget the sound it made), with him picking up a large piece of his thumb from the lawn (covered in bits of bright, green grass set in bright, red blood) and calmly telling me, "Kenny, get your mother". Which I did despite her being 8 months pregnant. Dad wrapped his hand and thumb in a towel and drove himself to the hospital. That's the only time I ever saw him voluntarily seek medical attention until his final illness a couple of years ago.
Anyway, that's the day I became a safety nut. I always read the manual and/or MSDS, have the right gear, and never short-cut a procedure. I've seen the consequences of impatience up close.
Food for thought…