This just happened to me last week.
My wife and I went to a small Mexican restaurant in an out-of-the-way part of town to have some Mexican food. It was recommended to us by a friend as having excellent authentic food. We entered, placed our order, then took our seats in a booth.
A few minutes later our food came and we started eating. We got about half way through the meal when, all of a sudden, I had to pee. But looking around, I saw no signs for a men's room. Instead, there was a sign that read 'men's rest room outside,' meaning you had to go out and around the back of the building to the room. So I got up and went outside to look for it.
When I found it the door was ajar and so I assumed it was not in use. I pushed the door open and walked in. There was no light in the place and it was very small. As soon as I stepped in I notice a guy was standing in front of the toilet. There were no stalls, partitions, and no urinal-just a toilet and a sink. I said, 'Excuse me, I didn't know it was occupied.'
He said, 'Don't worry. Come in and shut the door.' So I did. As soon as I got in and shut the door, he began to slowly turn around to face me. He had his cock out of his pants. He was not touching it. It was just hanging there, out of his fly. His balls were out too. We just looked at each other for thirty seconds, without saying anything. It was obvious he was there masturbating.
Without saying a word and still looking at me, he took his cock in his hand and began to fondle it gently. I was totally captured by this. Then he said, 'Take your cock out.' It was like a command. My heart begin to pound as I complied, slowly unzipped my pants, and pulled it out. He then said, 'Take your balls out, too.' And I did. Then he said, 'Do you want me to play with it?' WOW!
I had never done anything like this before! I am not gay, but I found that this was exciting beyond words. My cock was beginning to engorge and stiffen. I thought a minute and responded, 'Yes.' So he reached out and took my cock in his hand then began to rub the skin back and forth along the shaft, jacking me. In less than ten seconds my cock was like a rock and in thirty seconds my pre-cum was flowing and dripping off the tip. Then he said, 'Now you do it to me.' So I reached out and took his cock and began to jack him off.
We stood there for several minutes masturbating each other, getting more and more excited by the second. After we were both rock hard, we each took our own penises and began jacking ourselves. Very quickly, I began to approach the point of no return and, thrusting my hips out, jacked as if there was no tomorrow. He did the same. By now I had produced so much pre-cum that it covered my entire cock from the head to the base. My hand was dripping wet with it. It didn't take very long and I was squirting cum all over the rest room floor.
The guy didn't cum. He put his cock and balls back in his pants, zipped up, and left. I took the pee that I came in for, washed my hands, and left.
When I returned to the restaurant, my wife had finished her meal. I apologized for taking so long in the rest room and left it at that. I finished my meal, paid the bill, and we left.
I will never forget this experience. Maybe, some day I will return to the restaurant...alone. And wait in the small, dingy rest room.