At the outskirts of some woods near my home was a small shed just big enough for a couple of people to fit in.
The boys of the neighborhood would go into this shed to shoot a quick load. They would use it one at a time. You would sometimes see one or two boys waiting outside on their bikes while their friend was inside. Sometimes you would hear a loud grunt (or grunts), or maybe something more like a squeal. There would always be at least some very heavy breathing. Sound seemed to echo from that shed, even from the ones that were trying to be totally silent. He would step out, face flushed, after a couple of minutes (they always did it as quickly as possible), and his friend would then enter. The boy who just came out would inspect himself briefly for stray blobs of cum, then usually go a few yards away and pee on a tree.
I was a frequent user of the shed. I'd step inside and pull the door closed, but leave it open just a crack to let some light in. The wooden floor was spotty and discolored, as were the lower parts of the left and right walls. The left wall was the most used as it provided the most privacy (being opposite from the door opening). I'd usually try to last as long as I could while stroking continuously, but the thought that there must have been thousands of loads dropped in there, with a guy experiencing the sweetest feeling at that moment of release each time, was usually too much for me and I'd add another of my small loads to the shed's wall and floor. You could hear it splatter as it fell against the wood.
One time, I left the shed and one of the kids, John, was waiting outside. John, a few weeks prior, had apparently been caught by his mother doing it at home, and had been punished so severely that he didn't want to ever chance it around there again. The shed was the only time he could release his pent-up semen.
I greeted him, and he said Hi back then said he couldn't wait any longer. He went in, closed the door. I stood outside for some reason. Almost immediately, I could hear his hand slapping against his crotch as he stood inside the shed pleasuring his penis. Maybe a minute later, the slapping increased in speed and I heard three loud gasps. About a minute after that, the door creaked open, he stepped out. His eyes had a wild look to them. He smiled at me then said he had to go.
As soon as he got out of sight, I opened the door to the shed and looked down. The biggest puddle of semen I had ever seen was on the ground in the corner. I got a big boner right then and had to pull it out, then I masturbated again and made sure my semen landed in his. I zipped up, left the shed, and went over to my friend's house, my penis completely satisfied for the day.