As the OP says, it is a cop-out. When I was small it was always: "If you don't behave the policeman will come and lock you up". One day there was a knock at the front door. I must have been about four. When I went with my mother to open the door, there stood a policeman; the biggest guy I had ever seen. I really thought that he had come to lock me up. All I can remember saying, was, "Please Mr. Policeman, don't lock me up - I haven't been naughty for at least a week!