Your sister loves you more than anything in the world. She tells him how much she loves him every day, so much so that she even made him promise to marry her someday! But her problem is that her nipples are too sensitive. Just a touch of the elbow on her breast gets her so excited that she starts making babies with anyone. Her brother (you), who has even promised to marry her, is just watching as she has sex at home, succumbing to the pleasure and climaxing over and over again with her nipples.