When this mistress noticed that she had to scare this guy to get him to do things, she immediately felt that she had to make him eat her shit as that was the thing she knew he had never done and that she wanted to ensure that he did today. So she tied him, threw him down and she got on top of him and she turned him into a shit slave.
This guy was a con and he had conned this mistress. She was so mad at him and she had to torture him as much as she wanted to. The mistress felt that using him as her human toilet was the best way to do it. That is why she opted to cruelly tie him up and to make him eat her shit and drink her pee when she was done.