The brother suddenly comes into the sister's room saying, "Hey! Mommy told me to take a bath!" The sister is shocked and hides, saying, "I know, so don't come in without knocking!" and chases him out, then resumes masturbating. The brother says through the door, "I have no choice, stop masturbating and just take a bath." "How can you tell I'm masturbating?" "We're brother and sister, so I can tell by the sound!" The sister continues masturbating even after the brother leaves. She cums. After a while, the brother comes to check on her and finds that the sister has fallen asleep, exhausted from orgasm. The brother quietly gets excited by the sight and takes out his dick and starts stroking it. The sister wakes up to see her brother stroking his erect dick! The sister is furious that it's impossible for him to masturbate to her sister, but she calls out to her brother who is about to leave, apologizing and looking down. "You're going to masturbate to me in your room after this, right?" "How do you know?" "We're brother and sister, so I can tell. If you're going to use me as your wank anyway, I'll help you, so just cum here. But you have to promise me that this will be the last time you use me as your wank." "Okay." And so the brother strokes his dick, and the sister flashes her panties to be used as wank material...