It was the perfect plan. You found out what your big sister was up to at school, what she let those boys do with her juicy tits. It was her secret, and you'd hold it against her until she gave you what you wanted. You just couldn't get the image out of your head, not that you wanted to. Countless cocks sliding into her cleavage over and over. All of that cum drenching her chest. Now it was your turn.