There are 2 ways to play this game, solo or duo.
The player fills the bathtub up to the brim with water and shits in the bath tub and has to decide whether it's going to be a boat or a submarine. If you choose to vote for the boat you think that it will be a floater, if you choose submarine it will explore the deep underwater mysteries of your bath tub. If you guess incorrectly of whether it's going to sink or swim you have to lay in the bath till said boat/submarine disolves.
Two players both sit on the brim of the bath whilst the bath is fulled with water, both players drop their load into the bath and decide whether it's going to be a boat or a submarine. If chosen incorrectly the player that guessed incorrectly puts on their scuba diving gear and gets ready to discover some treasures.