Your step-sister is sick of hearing the rumors that you're a virgin loser, Zach, so she sneaks into your room at night to help you look less pathetic in your day to day. Clearly you haven't been getting your sexual frustration out, so she's going to show you the pleasure of edging for better release. She strips her clothes off and laughs that you think she might fuck you. Of course not, she's going to show you how to stroke yourself with a strap on.