I've jerked off in the spa a number of times, all of the water rushing around, sometimes my dick under a jet.
One time I was really horny and I know this is not good, but it was our spa at home and it was very clean.
I was lying on the seats, and I noticed one powerful jet was right near my asshole. You can guess what came next, no imagination required LOL, with a slight positioning, it shot water up my ass several times. It was not too much pressure, nothing like that, but it did give me a fast/great pulsating small enema, the water was pulsating because the air bubblier was on, that, got me super hot, shot cum all of the place, hot pulsating water up my ass, hot water rushing around my dick, it was like a masturbation machine.
Ha, later I tried to clean it, but there were too many little fragments of cum floating around and on the filter inlet, so I cleaned the whole thing again. I don't think I did it again, it was too much work cleaning it up.
Then, one time, I did a bag enema in the spa, that was very hot too! I took a good one in the spa, some of it leaked out, yep, another spa cleaning, LOL! It was about a 3 qt. enema, so I had to get to the toilet quickly, almost made it, but not completely. That, was real fun. Ha, my neighbors had no idea what was going on. Probably heard me cleaning the spa again ... them thinking, wow, that guy sure keeps his spa clean! LOL!