I had fun and I don't think she knew I saw her.
This happend four years ago while on a trip to Aruba with a friend. My buddy would go for a run early morning so I had about an hour to myself.
I was taking in some early morning rays on our deck, nude with only sunglasses and a ball cap. Our deck could only be seen by one or two others above and at the corner of the buidling right beside us. I stayed back from the edge so nobody on the ground could see me then while watching some girls out for an early walk I started to get hard.
I soon had a huge erection while enjoying the fact of being nude and almost in view when I noticed a pair of eyes above and over to one side looking at me. I was able to look out of the corner of my eye so she would not know I knew she was watching me. Now I was in full view.
I then had a great idea. I thought that if I was not being watched I was going to masturbate so why not pretend I did not see her and do it anyway. I slowly started to stroke my hard cock. The woman's head came even closer to the edge of the balcony for a better view. I was quite turned on by the fact a strange woman was watching me masturbate. I wanted to enjoy this as much as possible so I reached for my sunscreen and covered my cock with the white cream. I stroked my cock while laying back on the lounger for about 10 minutes and the woman never moved. Then I enjoyed a nice long orgasm and made sure I moved my body in a manner that showed I was having a great one.
After I came I just stayed there watching the woman who never moved. Soon a man came out onto the deck so I jumped up and went inside.
That was the only time I have ever masturbated in front of a stranger and it was a huge turn on.
I never told my buddy what I did.