Mistress Dula wanted to shit on this new slave as a way to not only humiliate him, but she also wanted to scare him as well. She felt that the best way for her to do so was to have him eat her poo. That way, he would never want to mess with her or incur her wrath. She was right on the money as that is what happened exactly.
Madame Du B was not happy to learn that her slave says bad things behind her back on a regular basis. She was not prepared to let him go in with that sort of behavior. So she used her big ass to punish him. He was eating cake for breakfast but she added her shit on top of it and she forced him to eat both the cake and the poo.