A father buys a lie detector that slaps people when they lie. He decided to test it out at dinner one night.

The father asks his son what he did that afternoon. The son replies “I just did some homework.” The robot slaps the son. The son then says “Okay, okay. I was at my friends house watching a movie.”

Dad asks “What movie were you watching?” The son replies “Finding Nemo”. The robot slaps the son. He then sais “Okay, okay. We were watching porn”

Dad said “What?! At your age I didn’t know what porn was.” The robot slaps the father. Mom laughs and says “Wow. He certainly is your son.”

The robot slaps the mother.

Edit: Fixed grammar + tenses.