LIE DETECTOR

Man buys a Lie detector robot that slaps people who lie.He decided to test it at dinner:Dad: Son where were you today during school hours?Son: At school (robot slaps son)Son: Okay I went to the movies!Dad: Which one?Son: Harry Potter (robot slaps again!)Son: Okay I was watching porn.Dad: What? When I was your age I didn't even know what porn was! (robot slaps dad)Mom: hahahahaha ! after all he is your Son!(robot slaps Mom).