When was the first time someone of the opposite sex saw you naked

The first time anyone saw me naked was in 2009 I was 14 y.o. and I was going to have some friends over only one of them had arrived, my friend Lacy. I told her I was going to take a shower and she could just watch T.V. in my room till I get out of the shower. So when I go out I went into my room with a towel around me and nicely asked her to go to the living room so I could change but she said she was vine and that I could get dressed and went back to watching T.V.. So I turned around and got clothes out I dropped my towel and could hear her giggle and I turned back around and she was look strait at me. I put on my shirt and then my underwear and she just keeped watching me the whole time. We talked about it for a while she showed me her boobs, but not in a sexual way in more of a she saw mine so she showed me her's kinda way. So my question is When was the first time someone of the opposite sex saw you naked? Excluding parents and Doctors. I mean like siblings, friends, significant others etc. Don't just put "when I was 8 years old" and thats it, give me a story, why were they able to see you naked?, what were you feeling? what happened? How, if at all, has it changed you? Thank You.