This happened when I was on my way home from college.
One afternoon I was walking home after college through the park that I always walk through, about half way through the park there was a toilet block, so needing to go I went into the men's toilet.
For some reason I've always had a problem with using urinals so I went into the end stall since the other one was occupied. I untied my shorts took them down a bit pulled out my cock and started to piss.
After a couple of seconds I heard a slapping sound and a soft moan from the next stall, this surprised me a bit so I looked over and saw there was a hole in the wall that I hadn't noticed! The guy in the other stall was watching me piss through the hole!
The hole was pretty big about the size of a fist so this guy got a good look at my cock! I got curious and bent over and looked through the hole and when I did he pushed his hard cock through the hole! I quickly drew back and looked at his cock sticking through the hole, I was actually getting really horny looking at his cock so I reached up and put my hand around it and started slowly wanking it! He moaned softly again as I was pulling his cock, he asked me to suck him but since this was the first time I was with a guy I said no.
As I was wanking him his cock grew harder, he was moaning louder now and from his movements I think he was pushing a finger or two in his ass! After a couple of minutes of this he just started cumming the first bit went straight into my mouth and across my cheek. I pulled away quickly still holding his cock then it throbbed in my hand and a larger spurt came out of it and hit my shirt! I kept wanking him until he stopped cumming then he pulled his softening dick back through the hole.
Hoping he would return the favour I put my near bursting cock through the hole but he just unlocked the door and walked out of the toilets just leaving me there covered in his cum! I was pretty bummed but I was so horny so I pulled my cock back a bit wrapped my hand around it and wanked myself off through the hole, it didn't take me long to blow just a couple of seconds! but it was the most intense orgasm I've ever had after I finished cumming I stood there for a second with my cock through the hole and caught my breath.
I opened the stall door and went to the sinks I took my shirt off and started to rinse the cum off it and then washed my face off. As I was doing this another guy walked in a gave me a real funny look, I stammered out with 'a bird shit on me and was just cleaning myself up', then he gave me another funny look then went into the stall that I just blew into! My heart started beating really fast and I just wanted to run out of there then he said 'must've been a big bird!' Then he opened the door of the stall I looked at him and he was standing there in front of me with his pants down rubbing his balls and bouncing his hard cock up and down! This started getting me horny again but he was pretty gross looking so I walked over took his cock in my hand gave him a few good wanks and said 'sorry but I have to go' and with that I left and went home.
I went back twice and had a bit more fun there but a few weeks later the walls were relaced with steel ones and the hole was gone. I would love to do it again sometime but alas nothing like that is around here anymore.