I should have put this under "when I was a kid" since I did this stuff for two years when I was 16-17. My best friends yard was like a resort having a pool, cabana, and basketball court. He was the oldest but had 4 sisters and a baby brother. In back of the cabana was a shower room with a sink and toilet in it. I went to his house once or twice a week year round and more often in the summer months. One of my parents would drop me off and pick me up so I always brought a change of clothes. Almost every time I was there I would shower before I went home never thinking about privacy in the shower. I started suspecting his oldest sister was peeking in at me somehow and after looking around the shower room many times discovered and opening in one of the boards. It was in the corner and right away I realized I could see outside so knew someone could certainly look in from the outside. Well, as it turned out, not only were 3 of his sisters peeking in at me but also most of their girlfriends. This is many years ago and why it didn't embarrass me I still don't know but got great pleasure knowing they were peeking in at me while I showered. The more often I knew they were watching me the more I exposed myself. I wasn't sure at that time how often they had seen me naked in the past but when I knew about it I would get an erection. I didn't try to hide it from them and after the first few times began letting them watch me masturbate. I became so brazen with it I would also urinate knowing they could see me. I did all this knowingly for just about two years. The following year I went away to college and have never done such a thing since then. I still today see my friends sisters at times but am still not embarrassed about it. I doubt if they ever realized I knew they were watching me and know my friend knows nothing about it either. It was a wierd time and when I knew they were seeing me naked it excited me and I would often masturbate at home just thinking of it. I knew at the time it was the wrong thing to do but it became such a turn on for me I couldn't resist. I know for sure that 3 of his sisters constantly watched me over those 2 years but am still not sure how many of their girlfriends did. I know there were quite a few but now don't remember who most of them are. I still live in the same town and sometimes I see girls who know me but I don't recognize them. My friends sisters and their friends are all in their 20's now and there are only a few I do recognize but still have no idea which ones saw me naked or watched me masturbate. Now that I am older I can imagine doing anything like that. Its something I'll never forget but also regret exposing myself as often as I did. It would have been simple for me to just hang clothes or a towel over the opening but I never did.