When her boyfriend wanted sex, she knew a good way to turn him off without hurting his ego. She did not feel like having sex so she pretended to be putting on a show for him as he loved that and especially her big round ass. She did it but as she bent over, she released a series of farts and he was automatically turned off and she got what she wanted.
This slave was perpetually late and this mistress did not want to keep forgiving him as he did not look like he wanted to change. So she had no option other than punishing him and she used her farts to do it. That was to be a warning to him that she would not tolerate his behavior and if he messed up again, she would do something worse and he would only have himself to blame.