I do this for a living... and the list I could post is quite long.....
Where to start?
When I was 11ish years old I was sanding some random piece of wood on a belt sander, probably a model part. My dad had taught me how to clamp the sander upside down on the bench so it could be used as a bench belt sander. So I was sanding away when I over-reached and my left forearm got drawn into the sander between the belt and the rear part of the guard (hand held sanders have a guard that wraps around the belt like a fender) it sucked the loose skin of my arm (grab the skin on the inside of your forearm and tug) and sanded through about 4 square inches of skin before I could turn off the sander. There was blood everywhere. I was home alone, my mom was out somewhere and my dad was out of town... There was no way to get ahold of anybody. This happened in 1974 and was pre mobile phone. Oh, did I mention that we lived on the island of Guam at the time, rather far from medical help? I walked over the neighbors and knocked, the neighbor lady answered the door, looked and me and promptly fainted... I eventually was driven by the Military Police to the Hospital and had to have a skin graft.... Still have the scar.
Overhead welding on a car that was on a lift. A large droplet of metal fell and some how got caught between the laces on my left boot, it burned right through the boot and into my foot, I was hopping around trying to get my boot off while the guys that worked for me were looking at me like I was crazy. The doctor looked at it and said something like 'it is nicely cauterized and removing the metal is pointless, keep it clean' I still have the metal droplet in my foot ( I know this due to another injury that had nothing to do with cars that involved x-raying my foot) and I still have the scar...
Got run over by a class A motorhome. Yep, went under the front wheel. Got my leg crushed and ribs broken.. It spontaneously started as I rolled under it to look at a starting problem... it was left in gear by the guy who parked it... That was a close one... No scars, well physical ones anyway, I still shiver when I see a 15 year old Winnebago...
Metal in your eye..... You don't know its there until about 3-4 days later when it starts rusting and you get a reaction to the rust...
Smashed fingernails... use a tiny drill-bit or a hot needle to pop a hole into your nail. It releases the pressure and the pain diminishes instantly... Some advise, don't do this while wearing your new khaki dockers as the blood can spray with some force...
Gosh, my business card says 'Tech Tyrant'