This just happened a few days ago and is 100% true.
This happened just a couple of weeks ago when my wife and I were taking a driving vacation. We stopped at a rest area to take a break and find some tourist information. The rest area was in an obscure location. It was mid-week, and not quite in-season. As a result the place was nearly deserted. There was only one other car in the lot when we arrived. My wife went inside the main building to look for information on local attractions while I went to use the facilities. The rest rooms were located in a separate small building off to the side. Both the men's room and, I assume, the women's room were the kind that allowed only a single occupant.
I went into the men's room, did my business, washed my hands, and left. However, just as I was passing by the woman's room I heard a light, feminine moan through its closed door. I paused to listen. A few moments later the woman moaned again, a bit louder than before. Was it the sound of bowel discomfort or was it something more? Her sound had an edge of arousal but it was hard to be sure.
I glanced toward the main building but there was no sign of anyone. I moved quietly toward the door, listening intently. It was silent for a moment and then I heard her gasp. 'Ohhh, yeahhh...' she hissed. My heart pounded. She was definitely making pleasure sounds. I could only imagine what she was doing in there.
Again it was quiet for a while. I heard some shuffling and then a metallic jangle, like the sound of a belt buckle hitting the floor. There was more silence and then she started to grunt softly. It was unbelievably erotic. As she got more into it, she got gradually louder and lounder. 'Ungh! Ungh! Ungh!...'
She sounded anxious, even hurried. It was like she really needed it and wanted to get to the good part as quickly as she could. Sometimes her sounds would stop for a few moments, but they would always resume soon, more anxious than before. After a couple of minutes she started to gasp 'Oh yeah! Oh yeah! Oh yeah!' over and over. 'Come on,' I thought to myself, 'You can do it.' 'Oh yeah! Oh yeah! Ohhh yeahhh!!!'
'That's it,' I encouraged her in my thoughts. 'You're almost there.'
Suddenly, she cried out rather loudly, 'Oh my Gawddd!!' Then slience. One second. Two seconds. Three seconds. Then: 'Aaaarrrrgggghhhh!!!...'
'Yes!' I smiled to myself. 'That's what you wanted!'
Her orgasmic cry was long and loud and beautifully uninhibited. There was a pause and then she groaned again, obviously still cumming. 'Unnnngggghhhh!!...' She finally finished with a long, low satisfied moan. It must have felt very good.
Afterwards there was silence. I regained my senses and started walking down the path toward the main building. I certainly didn't want her to open the door and find me standing right there. Also I had to believe my wife was wondering what had happened to me. Just before entering the main building I turned. Leaving the woman's room was a very attractive, smartly dressed woman in her early 30s. She had short black hair and smallish breasts. I thought about waving to her but instead I just went inside the building and didn't pay any more attention to her. However, that night, when I was making love to my wife in our motel room, I couldn't help thinking about that woman again and how intensely erotic it had been listening to her masturbate. I ended up having an exceptional orgasm myself.
Since then I've already masturbated many times to the memory of that incident. I'm sure I will masturbate to it many more times in the future. I have no idea who that woman was, but I thank her for sharing herself with me, even if she didn't realize she was doing so. I wish her many great orgasms in the future.