I can question authority of a judge, teacher or a politician. A policeman is a different animal usually unconcerned with your civil rights so come on and be real. A politician, not to be confused with a crook, is someone like ourselves who is willing to stick their neck out.
Kids aren't interested in what they are told as much as what they see. If there is one thing you could repeat is that evil is caused by ignorance. A better way to convey 'question authority' is to say "Don't look up at people. Don't look down on people. See them evenly and you will see life fairly".