9. Stealing The Flying Ford Anglia
Early in the second movie, The Chamber of Secrets, Harry and Ron missed the Hogwarts Express and decided to steal the Weasleys' flying car. They opted to follow the train to school but the journey was never bound to be smooth.
Both Ron and Harry were extremely reckless in the theft of the car as waiting a few minutes for the Weasleys to return would have solved their issue. At 12 years old, most people don't know how to drive a regular car, let alone a flying one.
In their journey, they were almost hit by the Hogwarts Express, Harry almost fell to his death and the Whomping Willow nearly crushed them when they crash landed. It was a completely reckless and idiotic decision that nearly got them killed, or worse expelled.