Lately I've been having some fun in the shower with a giant dildo w/ suction cup. Stick it on the shower wall, use lots of silicone lube (since it's waterproof) and I can ride my ass on it while shampooing.
Unfortunatley, the one I have (a Doc Johnson product) keeps unsticking from the wall at a crucial moment.
I just got this one yesterday because the suction cup was highly recommended.
It is HUGE! Bigger around than my fist, and longer than my forearm.
I stuck it to my shower wall, and it does not come off! I have to stick the end of a kitchen knife under the edge to break the vacuum. In the end, I left it stuck there, and this morning it's still there.
It took a few attempts to get this all the way in, but it might have been the best solo shower I ever took.
I'm going to take another shower. TTYL.
https://www.amazon.com/Black-Destroyer-Huge-Dildo-Pounder/dp/B008ATAO7W