Tyra wants to make a smoking-break and uses for this her slave as her seat.
She sits down first on his stomach, it's comfortable for her, but not for him with her weight pressing in his guts!
But Tyra wants to havo less comfortable for him, moves foreward over his chest (watch how small he's looking under the big lady) until she's sitting right on his throat, crushing his windpipe.
Not enough! She blows him the smoke in the nose, so he must cough...
coughing under 160lbs....
this made her bouncing with every cough...
and the windpipe-crushing more intensive ;-)