Step-sister Voyeur

I share the upper floor of our house with my step-sister. We have the separate rooms but we share a bathroom located just between them. There is a crack in the door. When we were just kids it was pretty up high, but as we grew up, we reached the point and now we could see through. I used to, when my sister who is a year older get through puberty, but I don't do it very often now. Recently I found she spied on me when I wank in the shower, I do it there regularly, often daily in the evenings, since the door lock in my room is broken and it could not be repaired. Often I saw her eye covering the light usually visible through the door spot, but I only turn myself and follow because I'm too horny to stop. She never commented I spend quite a time there and to be honest, I would like to watch her too, even as far as I know she doesn't masturbate in the bathroom. I don't mind this that much, sometimes I imagine her doing it thinking of me.

I have a good friend who always wanted to date her, but she wasn't into, simply because she was older than him. They never went out but he never stopped dreaming about her. Once when I was sleeping over in his house we were watching porn together and we started to talk about how often, where and when we masturbate. We were very horny, and later, lying in beds we followed to tell some dirty stories, mostly fantasies of ours. While I was stroking my dick under the cover I told him about how my sister watched me, what was probably the only realistic story of the evening. Soon we were done, but at the same moment he had the idea of walking on her while she is spying me, so he could ask her for a date. It sounded ok for me so the next day we arranged this trap.

He stayed over night as often. As every evening I went to the bathroom, feeling like a living target and started to wank. Maybe we were a little messy and noisy before, and she knew we are two of us, she didn't appear. Fine, I had a funny wank thinking what could go on outside. Late at night I heard him masturbating in his bed. We repeated it all more quietly next day and it worked. He caught her totally embarrassed spying on me and she was very happy to agree a date until he remained quiet about the whole incident.

They have been going together for a while. One day my friend told me she showed him how she masturbated in her room after finding out what I do in the bathroom. So the story completed, even he never told her how it all really happened.