Around five years ago my wife and I found a wonderful villa to stay in on the coast of Spain. It had great views of the mountains and sea and also a secluded pool area on two levels which meant that for most of the day when we were in we could swim and sunbathe nude. I had discovered nudism 25 years ago and treated this as a natural way of being, though my wife was still a little embarrassed at possibly being caught.
Two years ago I found that an old female friend and her partner were living near the villa and so we invited them over for a meal, drink and overnight stay. Though we hadn't seen each other for a while we had been good friends and I had introduced D to nudism on a shared Mediterranean holiday. When they arrived they told us that they were both into swimming and sunbathing in the nude and we said fine go ahead. We all had a relaxing afternoon, naked but with no sexual activity.
The next morning I got up early as usual and went down to the pool for a swim. After I went down to the lower level, out of sight, where I started to slowly jerk off while standing admiring the view and listening to music on my MP3 player.
D had clearly woken early too and I guess she heard me moving on the lower deck because she came round the corner. Seeing me naked with my back to her was no big thing but as her shadow swept across the desk I turned round to see who was there - and exposed all I had to her. I swiftly got my hands in front of my cock and apologised. She apologised too and turned to leave. I said not to go as I felt guilty and said not to worry. I then tried to just carry on a conversation with her as though nothing had happened - good weather, nice swim and so on. Because of this D stayed and sat down for a chat. The trouble was that after 5 minutes or so my erection was still as hard as ever and with no clothes or towel - and she had none either - I was still holding myself in with both hands, and failing to hide the situation. Eventually I said that holding my hands there wasn't hiding anything so I took them away and carried on talking. Inevitably D's eyes were drawn to my cock and we started to talk about erections on naturist beaches, feeling horny and eventually what I should do. By now we were pretty relaxed and so I asked if I could just carry on jerking off while we chatted. D agreed and so for about 10 minutes I lay back and gently stroked my cock while we talked. During this time D sat opposite me and with her legs opening more and more by the minute, obviously also enjoying the moment but without touching herself. Eventually I came. I apologised again to D (I'm not sure why) but she said that she had enjoyed it and was glad that it had happened.
After we both went to the pool area, I cleaned up and we went to get breakfast. We agreed not to tell out partners because what seemed to be quite natural may have been seen in the wrong way. For us it was just two friends together.