With real partner - just once.
When my Master another time invited me to his place, he said he is beyond horny, and will fuck me right in the hallway, without undressing - just lower my pants, and go. And boy oh boy, he must have been honest about "beyond horny" - I've never saw him moving with such speed, fucking me while I bent, leaning my hands on the wall.
At some point I feel my prostate becoming overstimulated, causing me to to feel the urge. I warned him, but he either didn't hear, or (more likely) just ignored. I didn't loose all control, but I couldn't hold a small stream, wetting the floor and my pants.
One of the my most intense experiences ever. Mix of relief from loosing a bit of bladder tension, shame and humiliation from wetting myself, additional arousal from all this scene... Also I loved feeling of urinating while being fucked - to be honest I wish him to repeat such fucking in the shower, so I can pee freely in the process.