It was leg day and he was cheating…..arching his back and rolling his shoulders. I had to show him the proper form, or as we continued to add weight he would injure himself. I told him to keep his shins perpendicular to the floor, keep his back straight and push back with his ass. I stood behind him to give him a target, told him to bush back until he felt resistance. The distance he had to push back was reduced with every rep as my boner started pushing out toward him, stretching my silkies. He must have felt my meat trying to spread his cheeks because his form was perfect, pushing that ass backward, hard. 

He increased the number of reps in each set without asking.