Dunno if "funny" is the right word for these, but:
- As a kid, I wanted to try if I could stick my finger under the needle in a sewing machine and pull it out faster than the needle comes back down. I could not. Apparently the doctor in the hospital described the injury as "nice zigzag threadwork".
- Still as a kid, we were playing "chicken" of a sort with a pushed lawnmower, the kind which has rotating blades along the axle, you push it to make the blades spin. We were jumping away from the front of it in the last minute. I jumped a bit too late. The bone in my big toe split into two parts right down the middle.
- As a slightly older kid, we tried rock climbing. I made it ~4 meters up a 5 meter rock face and slipped. Only a twisted ankle that time.
- Paintball as an even older "kid", I got shot in the mouth once, while only wearing goggles, no mask. That paint tastes bad, but no other injuries. Bought a mask the next day.