Riddle: A man and his wife were slowly driving along when their teenage son, who had just recently received his driver's license, suddenly drove his car up behind them and started to repeatedly smash into the back of their car, while his sister, who was in the car with him, loudly cheered and egged on her brother. Witnesses to the event appeared unaffected by the incident, and in fact some were even observed smiling. The police were never called. What was going on with this family, and why did no one call the police?
Answer: The man and his wife had taken their two children to an amusement park. The parents were in one bumper car, and their two children were in another bumper car.