Mistress Ann learned that her slave was being manipulative and she had to dominate him for it. She chose to teach him a lesson and she did it in a way that the guy had never expected. The mistress had him eat her shit and drink her pee in addition to other things. He had to do it all on camera and she threatened to make it public if he ever pissed her off again.
Mistress Ann was out to teach this guy a lesson no one had ever taught him. She had to make sure that the guy would learn his lesson the hard way and that is why she used her shit to punish as well as humiliate him. He was made to not only eat her shit, but he also had to lick her asshole clean in addition to drinking her pee.
Mistress Ann had a few secrets she did not want anyone to know. This guy came to know about them and he threatened to reveal them saying he could not keep quiet for long. The mistress was so pissed at him that she punished him by shitting on him. He was warned that the punishment would be worse if he went ahead and revealed any of her secrets to anyone.