A man buys a lie detector robot which slaps people who lie. He decides to test it during dinner.

DAD: Son, where were u today during school hours?

SON: At School. Robot slaps son!

SON: Ok, I lied, I went to the movies.

DAD: Which one?

SON: Toy Story.

Robot slaps son again!

SON: Ok, it was porn.

DAD: What?! When I was ur age, I didn’t even know what porn was..Robot slaps Dad!

MOM: Forgive him dear, after all he’s ur son. Robot slaps mom!