A man buys a lie detector robot that slaps people who lie. So he decides to try it out at dinner.
Dad asks his son, "Where were you today during school?" The son says, "At school." *Robot slaps son* "Ok, I went to the movies. "Dad says, "Which one? "The son says, "Toy Story." *Robot slaps son again* "Ok, it was A Day with a Porn Star. "Dad says, "WHAT?! When I was your age, I didn't even know what porn was." *Robot slaps dad* Mom says, "HAHA!! After all he is your son." *Robot slaps mom*