A man buys a lie detector robot that slaps people who lie...
The man decided to try it out at dinner.
Dad: Son, where were you during school hours?
Son: At school.
The robot slaps the son.
Son: Ok! I was at my friend's house watching a DVD.
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 didnt even know what porno was.
The robot slaps the dad.
Mom: HAHAHAHAHA. He is your son after all!
The robot slaps the mom.