Pretty sure the only times I can remember sitting down for a shower were complications of ketamine and mescaline. Sitting in the shower in the dark seems a little, different... You're not whipping yourself with chains or anything while in there I'm assuming
Dude, I sit in the shower all the time. Hot shower, cold tile against your back.
Then you can stretch your ballsack out so it holds water and you can pretend its a little pond and that your dick is a fishing rod.