Mistress Nica was out to dominate this guy and she felt that the best thing to do to the guy was to have him eat her shit as well as drink her pee. She did not care what he felt or give a damn about any of his cries. She went out of her way to make sure he ate her shit and she also jerked him off with her hands.
When mistress Nica asked this guy to be her human toilet and to eat and do all the nasty things she wanted, she had to enforce it. She did this by forcing this guy to eat her shit and to drink her pee. So she whipped him when he refused to do it and she made it cruel and painful for him by ballbusting him. He never messed up again after that.