Lie detecting robot

A man buys a lie detector robot that slaps people who lie. He decides to test it at dinner. DAD: Son, where were you today during school hours? SON: At school*Robot slaps Son* SON: OK,I went to the movies. DAD: Which one? SON: Toy Story*Robot slaps son again* SON: OK, it was paranormal 3. DAD: WHAT? When I was your age I wasnt even aloud to see scary movies until i was 18!*Robot slaps Dad* MOM: HAHA! After all he's your son.*Robot slaps mom*