I've mentioned this before, but I was hit with a sledgehammer head swung by my Dad.
When I was about 14, my parents started a kennel business. We had already built the dog kennels and runs, which were like flat pack furniture, but for the cattery he wanted to build his own runs, with each attached to its small kennel. So to do this he was going to drive 8 foot 2x4 timbers into the ground, to which wire netting would be attached. For the job, my Dad chose to use the heavier of two old sledgehammers he owned, presumably reasoning more mass would get the job done more quickly.
Now my Dad always bodged rather than making proper repairs and the head on the sledgehammer he chose to use had been bodged to the hammer shaft. - Several times.
Dad asked for help with the timbers, so whilst he is atop some step ladders with said sledgehammer driving the timber into the ground, my job was to hold it vertically. One time he swung the sledgehammer and the head came off, straight onto my head.
My Mum apparently thought he had killed me as he carried me into the house. As we lived around 12 miles from the nearest hospital he chose to drive there. I vaguely remember one part of the journey to the hospital, but most of the rest of the next 24 hours is lost.
I suspect if I lose my hair in that area, there will be decent a scar there.