Like many people the shower was where I did a lot of early masturbation but it might surprise you how I did it. I lay on my back and moved around until a particularly strong jet hit the tip of my penis. It produced unusually intense orgasms because the stimulation was constant. Using a hand, a toy or even a vagina you have to stop between thrusts but the water flowing constantly hits heights not much else can. Give it a try.
I do this with a hand-held shower head. There is a certain setting that gives just the right sensation on the tip of the penis and within seconds it feels like a prolonged orgasm that will have me doubled over. However, I have never actually ejaculated from this method. But dam does it feel good and the best part is that it’s repeatable!
In my younger days we only had a bathtub, no shower. We had a wand with a shower head attached to the spout. I usually got hard and I had trouble not playing with myself. Sometimes I would remove the shower head and pinch the end of the hose to aim the jet at the right place. It felt so nice it was impossible to hold off making myself cum one way or another. That was shortly before I started sucking myself and I managed to get the head in for very short times, another story
I find that holding the shower head behind me while I'm standing up with my legs open, and aimed up at the back of my arse and balls is a good one for getting me hard very quickly. I then aim the shower head slightly further forward so that it sprays the underside of my penis. Wow! That really gets me an instant erection. After that I usually hold the shower head to one side so that it sprays the side of my balls while I'm stroking. By constantly moving the shower head around while I'm pulling my cock and balls around means that the water jets hit nerves all over the place and set off some really nice tickly sensations. The best bit is when I can feel myself cumming. That's when I make sure to direct it at my balls and the underside of my prick. The tickling sensation from the water is like having someone lightly tickle your balls for you as you cum. It doesn't 'alf make me shoot!