There was a shower like this where I lived in Paris. Then again, everything in that bathroom was clogged and somehow connected. Poop would come shooting out of the sink when we flushed the toilet.
Hææ D: D: Har du fortsatt flashbacks?
Haha, ja. Men jeg fikk bearbeidet opplevelsen og gjort det om til en personlig bragd da jeg lykkes i å kommunisere med de franske rørleggerne (og fikk fiksa problemet!)~ matière fécale, oui oui ~
Techically though it's not the shower that's clogged, it's the drain. If you somehow managed to clog the shower, the last thing you would have to worry about would be poop floating up, quite the opposite, stench of poop would be preferred over your own body odor after some time :)