This happened many years ago, when I was thirteen.
That summer, my parents had this small pool in their backyard and all the kids in the neighborhood would spend hours and hours splashing and playing to keep cool. One of these kids was a girl named Sonia who had just moved in a few blocks down with her dad. Sonia was pretty, with long blonde hair and, although I was very shy and never let her know it, I had a crush on her. Her father was European and even though she didn't have an accent, there was something about her that made her mysterious and exciting. I don't know if it was my imagination or just wishful thinking, but I somehow felt that she didn't look at me the same way she looked at the other boys. She seemed older than the rest of us (although she herself could not have been older than twelve or thirteen).
Anyway, one afternoon, after all of the kids had gone home, I noticed that Sonia had left her swimsuit hanging on our clothesline. The sight of her sassy little bathing suit made me shiver with excitement. My cock was already rock hard, which was really nothing new since at the age of thirteen, I had an almost permanent hard-on. I had had my first wet dream about a year earlier and that past winter, I had discovered masturbation which, needless to say, I practiced more than daily.
My parents had gone out that afternoon and wouldn't be back until later that evening, so I had the whole house to myself. After carefully making sure that no neighbors were looking, I quickly took Sonia's suit off the line and hid it in a beach towel I had strategically draped around my shoulders. Of course, any neighbor with good eyesight would have plainly seen my huge erection practically jumping out of my own shorts. Having snatched my treasure, I walked through the back porch door into the cool dimness of the house.
I knew by the sheer excitement of my body (my heart was pounding like a drum, my hands were trembling and clear liquid was slowly oozing from the tip of my rock-hard dick) that if I masturbated, I would climax almost right away, which was not what I had in mind with the prize that I had in my hands. I therefore walked right into the bathroom (the closest room to where I was just then), laid Sonia's swimsuit on the edge of the sink, and proceeded to quickly jerk myself off to a quick and powerful orgasm. My cum had barely finished pumping out of my cock that I was already looking forward to the treat in store. In fact, I could feel my cock getting stiffer and harder already. This time though, I would be able to make my pleasure last (hopefully!) much longer.
After drying up the mess I had just made in the bathroom (it's amazing how my cum could sometimes travel several feet back then!), I took Sonia's swimsuit, walked up to my bedroom, shut the door behind me and drew the curtains.
A cool breeze was making the drapes billow occasionally, and as I stripped completely naked and jumped backward on to the bed with Sonia's swimsuit in my hands, I started fantasizing about her. Until then, I did most of my masturbating with a magazine (this was way before internet or video!) or using my fertile imagination. I never considered myself a fetishist per se, but having Sonia's still moist and cool swimsuit all to myself, alone in my room, with delicious thoughts of her running through my head was a definite turn-on!
I resisted the very first thing that I had an urge to do, which was to jerk off wildly into the crotch of her swimsuit. I could feel its silky lining with my fingers, and although I was woefully ignorant of the feel of the female anatomy at the time, I was certain that a girl's pussy must be absolutely the smoothest, silkiest thing in the world. I knew however that my pleasure would leave traces on the suit so I gave up that idea.
My second urge however, was just as tantalizing and, it turns out, much more erotic. With trembling hands, I brought Sonia's swimsuit close to my face and deeply inhaled the inside lining of her swimsuit, the one that only a short time earlier had been tightly covering her beautiful little cunt and ass.
As I continued to deeply breathe in and out (mostly in!), I started feeling strangely lightheaded (too much oxygen? or was it something else?). My penis seemed to be getting bigger and harder than I had ever felt it. My erection was practically straining away from my shaking body, twitching and throbbing deeply. Precum was freely oozing from the tip of my cock and the lubrication it provided allowed me to stroke harder and faster, which was driving me absolutely crazy with lust.
Still breathing in the faint smell of Sonia's cunt, with delicious visions of her cute ass and small breasts, imagining that I was mounting her like an animal from behind, I felt my balls start to rhythmically contract, letting me know that I was on the brink of reaching the point of no return, and that ejaculation was now inevitable. The throbbing got stronger and wave upon wave of pleasure was overwhelming me. I felt tears flowing down the side of my head. Finally, unable to take any more, I grunted very loudly and had one of the most powerful orgasms in my life. Before I realized what was happening, I ejaculated so hard that cum shot over my taut stomach and landed all over Sonia's swimsuit and on my pillow.
Totally spent and relieved, I had this sudden high and started laughing, feeling ooh soo good. I had no idea how long I had been laying in bed jerking off, and I knew I had to quickly clean off Sonia's suit, so I hobbled over to the bathroom and rinsed it off in the sink. After a few minutes of frantic rinsing and rubbing, I couldn't see any more stains, so I wrung the suit out and, after slipping on some shorts, went back outside and hung Sonia's swimsuit out to dry, again.
The next day, some kids came over, but unfortunately, Sonia didn't show up. Although it was totally irrational, I somehow had the idea that what I had done the day before had something to with her not coming to swim. That evening, after all the other kids had gone home, my mother took Sonia's suit inside and put it in our laundry room.
A few days later, Sonia came back for a swim. It turned out that she and her father had been away for a few days to visit relatives. I felt tremendous relief that Sonia's absence had nothing to do with what I had done. All of the kids had a great time playing in the pool that day, although I had to go inside the house quite often and spent a lot of time in the bathroom. I said I had stomach ache, but that I would be okay. For some reason, Sonia seemed to look at me kind of funny that day, and she certainly noticed my frequent absences.
Towards the end of the afternoon, the kids began heading home. At one point, Sonia went inside and got dressed, ready to leave. As she returned outside, my heart leapt. Ever so casually, Sonia hung up her sassy little bathing suit on the line, looked at me with her beautiful smile and said that her suit was still wet and would it be okay if she left it there to dry? I stammered that there was no problem. She answered something. For the life of me, I just can't remember what it was.