Mistress Kitty wanted to make sure that she had some shit and that she used it to dominate this guy. She did it in a way the guy never anticipated and she cruelly turned him into a loser. The mistress cruelly made him eat shit and it was brutal for him as it had never happened to him before. He never expected that from him and he had to learn his lesson.
Mistress Kitty does not like her boyfriends to be boring. She is after adventure and a good time. So she had to make sure that she got that from her man. When she did not, she told him and they agreed. He did not follow up on their agreement and she was pissed. To make sure he would never forget again, the mistress made him eat some of her shit.