One of many times I did this on a slow night at work.
A few years back when I was younger I use to work for a department store in the warehouse. I usually worked the day shift but since I was now going to college during the day my hours got shifted to the night shift and it was a lot slower and quieter during the night.
On one very slow night a few hours before closing I got very horny and, being all alone on in the back shipping house, I looked for a place to drop my pants and shoot my load, I figured it was too risky doing it in the open warehouse so I looked for a better place to shoot my cum.
I found a nice place. It was located in the employee's bathroom of the restaurant that was connected to the store I worked in. It was a single little, dirty, nasty, smelly restroom. The kind of restroom where if you pissed on the floor it wouldn't matter. As I locked the door behind me I was shaking with excitement, I first took off my shirt then I dropped my pants, I could see my cock pressing out against my briefs, I lowered my undies past my knees, my cock was as hard as ever.
I grabbed it and began to stroke it slowly until I felt a nice warm flow of my precum start to drip down my shaft. I was so excited cause I knew this was going to be a great cum, just the thought of being in that dirty little room got me so worked up. I pumped my cock faster and faster untill I couldn't take it any more, I bent over and inserted a finger in my hole as I began to shoot wad after wad of cum all over that dirty little toilet and floor.
When I was done there was cum dripping off of the toilet, it was a site to see. I got my self cleaned up and left that room feeling proud of the mess I had made of it. I told a buddy of mine that I worked with what I had done that night, and the next day when I seen him he told me that he had done the same thing that morning and to go check it out, so I did and there it was in that little piss hole bathroom, cum dripping off the toilet and on the floor. We both had many good times in that dirty, little room.