You must have heard her cum a million times by now. It's incredible how your step-sister finds all that time to masturbate every time you're within hearing distance. At this point, you're absolutely sure she WANTS you to listen. But you never expected what happened this afternoon. You come home to find her masturbating on the couch. She's got the window open so anyone can look in and see. But she knows your schedule, and that you're ALWAYS home at this time. She threatens to get you into real trouble if you don't obey. She gets off, let's you watch, but doesn't let you touch; you get cucked by her vibrators.