Having an affair with the girlfriend's sister, after visiting his girlfriend's house a few times, the young man caught the attention of her sister. Today, he went to his girlfriend's house again, and they talked for a while until he had to go outside for an errand, leaving just him and the girlfriend's sister at home. Shortly after the girlfriend stepped out of the house, the lustful sister called the young man over and asked him to blow her horn. When the girlfriend's sister made her request, how could he refuse? He decided to please her instead.