Back when I was still living at home my mother's friend Mary ran into some problems in life, and needed a place to stay for a few weeks until she could get her affairs back in order. Ever the helpful person, my mother let her stay at our place for as long as she needed. We converted the downstairs family room into her own private apartment, moving out some of the furniture to give her some room and moving in a spare bed and dresser. It was a makeshift residence, but it was only supposed to be for a few weeks. In reality, we didn't use the downstairs all that much, so Mary moving in down there wasn't much of a burden on us. There was a small combination laundry and bathroom attached to the family room, which had a second door right near the stairs, so our family could still use this room without having to go through her little apartment.
I had always taken my showers at night before bed, and used this downstairs bathroom rather than the one upstairs. So when Mary moved in with us, that first night before bed like usual I went down for my shower. She had gone to bed a short bit before, so I quietly entered the bathroom through the other door, not wanting to wake her up. The way this bathroom is laid out is that the shower stall is right next to the door that empties out into the family room, which is where Mary was. Her bed was on that side of the room as well, with the head of the bed right next to the bathroom door. So as I got undressed and stood in front of the shower right next to the door, it occurred to me that as she lay in bed her head was only about three or four feet away from my bare genitals.
I had a bit of fun with that thought when I realized it, the only thing hiding me from her being that thinly constructed wall. I turned to face in her direction and wiggled my dick back and forth as if she could see me. Lying on her pillow her head was at the same level as my privates. As a guy of about 20 at the time, I pretty much masturbated every single day, and I usually did it during my nightly shower. So it being that time of day to take care of myself, I was on the verge of doing it in the shower while she was lying but a few feet away. The idea of being that close to her while I jacked off certainly gave me a thrill. Would she know what I was actually doing to myself in the shower?
But before I reached into the shower to turn on the water, through the thin wall and door I very clearly heard her move about in her bed. I realized that any little sound I made she would hear as well, especially with how quiet it was this late at night. So here I was, a horny young man moments away from stroking himself, with an attractive lady just a few feet away behind a door, who would hear any sound I made. The conclusion was obvious: Instead of masturbating in the shower with the water to drown out my sounds, I decided to do it standing right next to the door, without the water, mere feet from her so she could hear every sound I made. This was an exhibitionist's dream come true.
The wall between the bathroom and family room was extremely thin. The bathroom had been added a few years ago, and the wall we put up was just a few thin pieces of paneling without any insulation to block out sound. There was also a bit of a gap at the bottom of the door, so between the gap and the thin walls, any tiny sound I made I knew she could hear quite well. And I'm sure she could tell I was standing right next to the door by the shadow that snuck through the crack at the bottom. Just thinking about the proximity to her had made me hard, so I began to lube myself up nice and good, and slowly began to stroke my penis.
With the stillness of the night, how noisy that was! I stroked it slowly and quietly at first, sort of testing the waters of how obvious this was; and it was very obvious, let me tell you. But the idea of what I was doing to myself and what she could hear me doing to myself quickly did away with any cautiousness on my part, especially when I heard her turn herself over, almost as if leaning up to be certain of what she was actually hearing. Having her attention now, the exhibitionist came alive, and I started going at it normal pace.