Got the tip of my finger cut off in a door when I was 8 and the tip had to be sewed back on.
Around the same age, we had a family vacation to Disney World. While waiting to exit Big Thunder Mountain, I decided to go to the car in front of me and exit through that one, as it seemed empty and my sister next to me was taking too long for my liking. The only problem was that I did not realize that the cars were spaced apart (hey, it was really dark in the ride load out area for an 8 year old! ). So instead of walking through a car in front of me, I walked between the cars and fell onto the track! I still have a scar under my arm and my knee from cuts that I got, but luckily those were the only injuries from being a stupid, unobservant kid. When I go on that ride now, I don't know how I managed to miss that the cars had space in between them.
The most annoying injury happened last year, when I tripped over one of my cat's toys and fractured a tiny bone in my foot. They could barely see the fracture on the xray, but I still have a bump on my foot that's not supposed to be there. And if I'm on my feet for a long time, my foot will really hurt. For such a minor injury, it's still giving me a lot of trouble and pain.