My beautiful older sister, who is much older than me, still treats me like a child. She interferes with my studies and private life, and when she suddenly comes in while I'm taking a bath and sees my uncircumcised penis, she says, "You have to wash it properly!" and pulls back the foreskin and washes it! My penis also gets erect! When my sister sees this, she gets excited and moves her hand, and I cum on her because it feels so good! Just when I thought this was bad, my sister, who is in heat, says, "Hey... let's do something more adult..." and makes a super erotic face that I've never seen before.