I have an above ground swimming pool in my back yard, and when I have to clean the bottom of the pool I use a long hose that is connected to the skimmer of the pool that uses the suction from the filter pump to suck the dirt off the bottom of the pool. The suction is water not air. I was cleaning the bottom of the pool one day when I put my hand at the opening of the hose to feel if the suction was working. Get too much junk in the skimmer the suction goes down.
The suction felt great because it was water.
I got an immediate hard on, so I pull my swim suit off and stuck my raging hard on into the opening of the hose. I almost blew my load right then and there. The water being sucked into the hose around my cock felt incredible. Just like a very wet pussy wrapped around your cock but it had a sucking action. When I did blow my load, I almost passed out it was soo awesome. The best part about it is, there is no mess to clean up. It goes right into the filter. All I have to do is backwash the filter into my backyard to clean out the filter. No mess in the pool.