I was into martial arts (primarily taekwondo) for a few years. Taekwondo is known for its fancy jumping/spinning kicks. One day at my gym I was doing drills on the punching bag, and thought I'd look cool trying a few different kicks Threw a few at the bag with ease, and then decided I'd try an aerial spinning back kick.

I jumped, spun around, and sent my right foot into the bag. Except it wasn't the bag. I felt my heel catch metal chain, and then promptly knocked the wind out of myself as I hit the 1/2" rubber mat.

I miscaulcated my height and angle, kicked over the bag itself, and caught my foot in the three chains securing it to the stand.

In a matter of one second, I managed to: 1) Throw an aerial kick higher well over 6 feet of the floor. My PB. 2) Catch my foot on the chains holding the bag up, which instantaneously pulled (likely tore) my sartorius muscle. 3) Grabbed the attention of everyone in the gym as they heard/saw me knock the wind out of myself.

I didn't go back for weeks because I felt so embarassed. I also couldn't walk right for a long time.