The Splatoon development team was planning to integrate some amusing toilet humor into the game, as concept art in the huge official artbook reveals. Check out the page below, which showed an early concept that would allow Inklings to use urinals as a warp zone in squid form.
Sadly, the final product did not use this mechanic. But we can only dream of someday being able to flush our squids down the toilet to warp them to places far, far away. Would you play an entire game based around helping a poor Inkling escape from the serpentine labyrinth of the Inkopolis sewer system after being lost to a urinal warp?
Source: Destructoid
I would buy that as a DLC solo campaign in a heartbeat.