This mistress had eaten a very expensive meal the previous night and she felt like shitting. When she remembered how expensive it was, she did not want to shit it all out and let it go down the drain. She wanted it to be used so she called her slave and made him eat her shit. She had him lay down and she shit into his mouth and he ate it.
Princess Nikki's method of slave humiliation differs significantly from other mistress'. She does not shit directly into the mouth of a slave. Rather, she wants it look like it is the slave who wants it. So she shits into the hands of a slave and the slave in turn eats the shit from his own mouth. That looks better and not as if the slave is forced to eat the shit.