One of the greatest humiliations a dominatrix can give her slave is to use him as her living toilet. Living toilet education is called toilet slave training
The slave has the honor of lying under a toilet bowl and having his mouth sprayed with the toilet drain. Often he is also tied up so that he cannot escape from what is coming, and then the mistress sits on the toilet, if the slave is lucky he can even see her sex, which he normally can never see, and pisses in the slave's mouth.
In his helpless situation the slave has no choice but to swallow all the piss. It is always a pleasure for the true slave to be abused as a urinal.
A large selection of toilet fetish clips can be found here: Human toilet