Father buys a lie detector[129] that makes a loud beep whenever somebody tells a lie. The son comes home in the afternoon. Father asks him, «So, you were at school today, right?» Son: «Yeah.» Detector: «Beep.» Son: «OK, OK, I was in a cinema.» Detector: «Beep.» Son: «Alright, I went for a beer with my friends.» Father: «What?! At your age, I didn’t touch alcohol!» Detector: «Beep.» Mother laughs: «Ha ha ha, well, he really is your son!» Detector: «Beep.»
