This is the description of a real fact happened to me twenty years ago when I was fourteen. At that time, I was living with my family in small town in southern Germany. During the summer it was customary to go to the local open swimming pool to meet friends and have a good time. But one thing made it even more interesting to me, that is, the stalls where people went to change, were made of flimsy metal sheets with small holes made by voyeurs. I spent several hours spying on young girls and women while they were changing in their swimming gear.
I must say that it was a great learning lesson for an adolescent. I learned first hand how women looked like, I observe them naked, in their most intimate moment even while replacing their tampons before entering the pool! Of course, while engaged in these secret observations, I masturbated like crazy. To avoid embarrassing situations, before entering the stall, I sat on a bench and monitored who went into the stall. I did not want an adult watching me, while I was doing my things. Well, one day I saw this lanky blondish girl entering the stall. She was perhaps a bit younger then I was and really cute. Immediately, I grabbed the opportunity at hand and entered the stall next to her. I hanged my towel so that the hole in the wall between us would be covered. After a few minutes, I slowly moved the towel aside and to my surprise I saw the young girl spying into the other stall confining with hers.
She was naked, just an adolescent like me. She had small tits and a few blond hair on her pussy. Finally that was the moment I was waiting! I jiggled the hanger with the towel on, making some noise to surreptitiously attract her attention. I slid the towel aside so that the hole was now fully uncovered. I could see that she was there, spying on me, because the hole became dark when she put her eye against it. I proceeded to expose myself to her. Of course she did not know that I knew. I stripped naked, showing my rather athletic body and my erect cock in all his glory. I began to pump my hard-on with vigor. The tip of my penis must have been less than twenty inches from her eye. I really displayed myself in all possible way, rubbing my balls, sticking a finger in my anus, stretching the skin of my cock and rubbing precum on the cock's head. Finally I exploded, ejaculating an enormous amount of cum on the towel. I collapsed on the bench totally satisfied.
Hidden from her view, I took a sheet of paper from my school book and wrote in large characters 'I hope you enjoyed it. Now it is your turn!' I stood up and slowly put the paper in front of the hole. In an instant her eye disappeared from the hole. I waited, then slowly I approached the hole again. Her eye was there, but as soon I approached she retreated. To my delight she had chosen to reciprocate. With a sign, she asked me to throw the towel where I ejaculated under the stall to her. She lifted the towel to her nose to smell the wet stain of sperm, then she opened her pussy lips to my gaze, showing me the entrance of her vagina. She inserted her middle finger into her vagina, while rubbing her clit. She did all I was hoping for. With slow circular motion she pleasured herself until I saw her stiffening up an letting out a soft moan. She finished all by cupping her labia and rubbing them in ecstasy. That was the first time I saw a girl masturbating. She blew me a kiss, quickly dressed up and left the stall. I never saw her again.