Cadence and Ruby have their pig wallowing on the floor. He gratefully oinks while eating whatever slop of food they have tossed on the floor, and the girls respond to his gratitude by grinding their heels into his back. The pig's back is already scarred from previous at the hands of the girls but that's of little concern to them, their heels need a place to grind and the flesh of his back is the perfect location for that.