Your hot step sister wants a bubble butt and since you are always at the gym she comes to you for help. You start by having her learn the basics. squatting. But you'll be able to help better if she does it over your face. You've got her working hard so you encourage her to take off her yoga pants so you can get a better look. Soon she's bouncing her booty all over and catches you jerking off. You are both turned on and start fucking. Having her ride your cock in the perfect ass viewing positions and then taking control until you both cum.