In this adult sibling role-play, my younger sister is now portrayed as an adult student but still insists on bathing with me. It is a problem because our tub is so cramped that her huge tits keep rubbing against my body, making my cock hard despite our forbidden relationship. She notices my erection, but instead of pulling away, she becomes fascinated by it and says she wants me to put it inside her. Unable to resist, we cross the line into taboo sibling sex.