I caused a very small fracture in my wrist when I smacked a girls ass really hard over her jeans. I am not sure what happened but I suspect I hit a snap on her jeans or something, it did not hurt at the time but I was sore the next day and had to get some X-rays and an MRI when it still hurt weeks later. Ended up with a little brace and I wore it for about a week and it felt better.

Doctor: What happened?
Me: uhmm fell down some stairs

This story is a lot better when heavily exaggerated and embellished by a friend of mine who likes to retell my stories with all the details changed to be more interesting.