Mistress Mystique felt that this slave was too lazy for her and she humiliated him cruelly. She did this using her farts. In addition to the farts he had to smell, the mistress ensured that he also licked her asshole. She had a sweaty ass being a big assed mistress and there was a little smell ass well and he had to lick all of that. He had no option.
Mistress Mystique has a huge ass and she loves to smother people with it. This is especially done to those who have a crush on her and her big ass but she does not like them or their vibe. This guy was one such person and she enjoyed smothering his face with her big ass and also farting on him for good measure. He tried to plead his case but she ignored him.
Mistress Mystique wanted to do something naughty because her boyfriend loved it. He also loved her ass and she wanted to use it to do the naughty thing she wanted to do. So the mistress spread her ass and she made her boyfriend bury his face in it and he loved it that he was instantly turned on and he almost came as she wiggled her ass on his face.