Ok, I have two things I would like to submit. A clean-up technique and a shower jacking technique.
One, day, while in the shower, my younger sister had about 6 foam cans. Being 9 and very curious, I put a whole bunch of the foam on my penis and it became hard as a rock. This quickly became my favorite way to jack, but as long as you have a lot a foam and and very little water touching your area, you'll get the same great sensation I still do, till this day.
And for the clean-up technique, I don't always use soap or foam when jacking in the shower, just the water. And anybody who lies down in the shower, while jacking, knows clean-up can be a real pain in the you-know-where. So, I found that out of anything, Apricot Scrub and Selsen Blue, the drandruff shampoo work the best.