This role-play is performed by adults. My younger sister saw me masturbating and I hid it in a hurry, and she said, ``I know that much too! Shall I do it for you?''... an unexpected suggestion! If you give me a hand job, I'll ejaculate in seconds! However, my younger sister was wondering about my dick not stopping even after I ejaculated, and when I made a desperate excuse, saying, ``I can't stop it from cumming with a hand job like that,'' my younger sister started sucking my dick this time. As expected, she also ejaculates with a blow job. This time, my sister's expression completely changed! ? ``I have to go all the way to the end...'' and ends up crossing the forbidden line...