Although it may not be an embarrassing but it really is a MOMENT which I remember since childhood. I was almost 5-6 years of age when I used to go to water springs near our village with my elder brother and his friends. My bro and older boys used to swim in rather deep water while me and some other young kids enjoyed in shallow waters. One day I went near my bro and suddenly felt there is no ground under my feet and I was fully immersed in water
..... Although it was a good experience seeing underwater but soon I wasn't able to hold breath anymore so I grabbed my bro and jumped up. Soon my head was above water and I took a couple of huge breaths and was again under water 
So I kept jumping like this for quite some time and my bro didn't knew it as he was busy in chit chat with friends.. I was tired of jumping and calling him when luckily he spotted me and took me to shallow waters again ....
I still love swimming more than anything and really remember and miss those days now 