whoever shits in the fucking shower is disgusting. apparently, 1 in 30 people shit in the fucking shower. please if you need to fucking shit just shit on the toilet. its that easy. if you're already in the shower and you need to shit please get out of the shower, dry your ass and take the shit. 
wait for the shower to warm up. while you're waiting, take the shit you need to take. that's another way to stop shower shitting. 
for your concern, peeing in the shower is ok i guess but it's still gross. just don't piss or shit in the shower. 
we can fix this. we can stop shower shitting. thank you for listening.