Knocked out

When I was 28 I was visiting my OH relatives, her cousins and her aunts were at the home. One of her cousins was a lot younger than us, he was like 10 or 11. He was there with is friend who was same age as them and they were practising karate. So I put on the armor and decided to have a spar with the little guy as he was new to the karate. After I got on the body armor and the helmet, which had a gap at the jaw, about 10 seconds later, he hit me right on the jaw with an open hand and I was out like a light. I tried to find some excuses but couldn't come up with any.