Personally? I'm pretty lucky, but I'd say when I got my fingernails pulled back trying to strip a stupid big black running back last year in football. Like 2 of them came completely off. Now I wear gloves lols.
Worst I've ever heard, was when my uncle got hit on the head with a piece of dead fall. It broke his helmet, fractured his skull and compressed 4 of his vertebrae(like squished all the gooey bits out) and tore his chest and back muscles and compound fractured one of his shins. He was auditing a lot by himself right before he was supposed to go home, woke up right before sunset(middle of fall, nights are cold) had to drag himself back to the truck so he didn't die and radioed for help. Passed out from the pain in the cab of the truck, woke up 2 days later in the hospital.
Since then he's had 4 back surgeries to remove the damaged disks. He's got a metal cage surrounding his lumbar region now to keep all the goop in place and they removed 2 vertebrae so he's a couple inches shorter now. Still goes and chops wood like a boss though.