I’m totally going to regret posting this, but I’ve tried peeing over my shoulder before and I can confirm it’s impossible. There’s a lot more at play than pee velocity. For me, once you aim it up to go over, it significantly reduced the amount of pressure I was able to push out. I was able to get it about up to my nipple, so it may be possible to do some “cool” over the arm type shots, but over your shoulder/head doesn’t seem possible from my test.