When I was 10ish, and thus a moron, we found some paving stones, and being morons, decided that breaking them is cool.

So we throw them up into the air, and watch them shatter. My uncoordinated ass throws it up, and it lands smack on the top of my head. Got me a big concussion and permanent spinal damage, leading to my having periodic debilitating neck and shoulder pains basically till I was 22ish and the doctor prescribed weightlifting in addition to muscle relaxants.

On the down side, damaged spine. On the upside, great motivation to consistently hit the gym, haven’t had neck pains in over a decade! On the down side, no cute clothes for girls who do upper body day.