Of course. Sometimes the piss doesn't want to come until after you've gone in the shower. You think I'm going to hold it? Or jump out into the freezing cold of my bathroom? Fuck that. You are in the shower constantly getting rinsed off. Even if some piss gets on you it's washed away instantly. All water gets drained into the same location so what difference does it make if you piss in the toilet or shower?
Weak minds.