You have a brother, and he has a friend. They are both 17 years old. One day, when his parents were away, his friend came into the apartment. He will be with him for the night. Your brother didn't even ask if you mind. He obviously doesn't care. You were sitting in your parents' room and watching TV. Suddenly, his friend sits next to you while your brother is cooking. You can see a sly smile on his face.