You are approached by your sister because she knows that you like to spy on her and knows when you do it. She wants you to do exactly as she says as she teases her body to you never showing you nudity until the end if she decides if you have been good enough or not. she gives you joi making sure you repeat words after her and telling you to keep going. She slowly strips off her dress carful to not have any slips before the very end when you are going to cum and she lets the dress fall and you cum all over her tits.