The most embarrassing moment

I've past for a lot stupid and embarrasing moments because sometimes I get so nervous and anxious when I have to do things I'm not good at.
Something that has always been dificult to me is the physical exercice (even now hahaha cause I'm on a CFG that's call Physical conditioning and it's SO hard I don't know why I get into it).

Well the context is on eight grade. I was different, more fat and more shy. On school we were in that unit in which you have to do some somersaults (I really hate it). I don't know why but all my classmates were good at it and just I was the weird that couldn't do it. So on some weeks will be the test and I practice as lot on my home  and my mom and dad help me. The test consist on make the invert (that hard exercise in which you have to stand up with your hands).
Finally arrived the day of the test and I was the last on the list so I have to see all my classmates making amazing the exercise. It was my turn I was so nervous and well I tried it and the teacher has next to me to take my legs to help me with the exercise and then... I put my legs up and I hit teacher on her head, everyone laughed and I was so ashamed. My friends still remind it.