My step sister's alluring underwear and sensuous milk cans enticed me

I had no idea what was in store when my wondrous stepsister demonstrated up at the gym, exposing her brilliant bootie and mouth-watering bra-stuffers thru her see-through lingerie. As I struggled to struggle back her seduction, she skillfully gave me a mind-blowing arm job before riding me rock-hard in both cowgirl and change sides cowgirl positions.