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. [The robot slaps the son.]
Son: Ok! I watched a DVD at my mates.
Dad: Which one?
Son: Kung Fu Panda. [The robot slaps the son again.]
Son: Ok! It was a porno.
Dad: WHAT? When I was your age I didn’t even know what porn was! [The robot slaps the Dad.]
Mom: Hahahahaha! After all he’s your son. [The robot slaps the mom.]