When I was 8 I went on holiday to a UK resort and it was on the second day in, my family decided to go biking. Being young and with my older brother we decided to see who could go the fastest down a hill. As I came to a curve in the hill, I went to brake and realised the brakes weren’t working and I was unable to stop which resulted in crashing into a post on the hill.
I was flung upwards and I came down on top of the bike, at this time the gears were still rotating at the speed I had been going and my middle right finger went into the them and the top half was all but cut off. The scar that formed was a combination of the original hospital I was sent to immediately afterwards not dealing with the wound correctly and the second hospital near where I lived at the time having to re-damage the finger to the original injury and then stitching it together correctly.
I love it however as I often make up stories about how it occurred before telling the real version and the fact I now have three fingerprints on one finger!