Similar stories here.
On one occasion I was in a pub at Victoria Station, in London, with some mates. I went for a piss and realised that this tall lad at the other end of the urinals was taking a look at my cock as I pissed. I looked back, he pulled his out to full length, gave it a stroke and grinned at me. We both zipped up and left. The next time that I went for a piss he followed me in. The same thing occurred. We went back to the bar, I was with my group, he was across the bar with another guy and two women. The next time that I went for a piss he followed me again, this time he stood next to me and pissed and said that he thought that I'd got a great cock. I returned the compliment and let him play with mine, which developed into a full scale wank as we both stood next to each other hammering away at our own cocks and eventually both cumming in the urinal. He said that he'd like to do it again, apologised for not being able to hang around as he was on a night out with his girlfriend and his mate and his girlfriend!
Also, I've often gone to watch the rugby matches in Cardiff (Wales), especially when England play there. The toilets at the station are woefully inadequate for the volumes of people returning home after the match (after much drinking). On both main platforms the toilets have two urinals, two stalls and a sink. It's not uncommon to see guys pairing up at the urinals and in the stalls and the sink is regularly used as an additional urinal. I've been in the stalls and been joined by complete strangers who've pulled out their cocks and pissed and talked to me. It's impossible not to get a good eyeful of cock in that situation (especially for them - I'm 6' 5"). On one occasion I was pissing in the sink with a couple of other lads, all (as far as I know!) straight but admiring each other's cocks - afterwards one of the lads followed me along the station platform and told me that I'd got a really impressive cock and would I be interested in a threesome with him and his wife? He said that his wife would really appreciate being serviced by a big cock and that he'd like to see me pounding into her while he wanked off or let her suck him. His timing wasn't good, so I couldn't take them up on the offer.
On another, non-public occasion, I had a similar situation after a night out drinking with a college mate. We got back to the house and both made a bolt for the toilet. He got there first and didn't lock the door, so I followed him in. My mate had his cock out, his foreskin pulled back and was in full flow, with his back to me. After a bit of teasing and friendly pushing and shoving he suddenly grabbed my right arm, pulled it around the front of him (and me up against him, so I was looking right over his shoulder) and put my hand right in his piss stream. It was quite funny at the time (and very out of character!) and quite horny - once he'd finished pissing he had quite an erection developing, as had I when I got my cock out. He hung around in the bathroom whilst I pissed, still with his cock hanging out, and then after I'd finished we both ended up standing around the toilet and having a damned good wank, both shooting our spunk into the toilet at about the same time. We both gave our cocks a wash, put them away, went back downstairs, grabbed another beer and it's never been spoken of since. He's been happily married for years with a family.
Which just goes to prove that labels mean nothing!