A man buys a robot that slaps people when they tell a lie.

He decides to test it on his family at dinner that night. The man asked his son, "Son, what did you do after school today?" The son replied, "Oh, I just did some homework" and the robot slapped the son. The son said, "Okay I actually watched a movie with my friends". The father asked, "What was the movie?" The son said, "Star Wars, Episode 5". The robot slapped the son. The son stammered "Okay it was Showgirls". The father laughed, "Ugh, I would never watch movies like that". The robot slapped the dad. The mom laughed, "He certainly is your son". The robot slapped the mom.