That's what we used to chant when I was a kid, although the connection between perfidy and accidental arson was not exactly clear in our minds. Ever since, people have been trying to create a reliable lie detector. The latest entry, according to an interesting article in a recent The New Yorker, is manufactured by an Israeli company, Nemesysco. It uses "layered voice analysis," which analyzes 130 parameters of speech in order to determine the speaker's psychological state. The device failed two independent tests, but is nonetheless selling to law-enforcement agencies around the world. Also to insurance agencies, to detect fraud. But if the device fails tests...
More reliable is a device developed by Sound Intelligence, and which has been installed in public areas in Rotterdam and Amsterdam in the Netherlands and in Coventry, England. This one detects not lies but aggression. It picks up the sounds of people shouting and -- this is the part that interested me -- can distinguish between actual anger and actors pretending anger. Apparently genuine anger overstresses the vocal chords and produces different kinds of sounds than even, say, Lawrence Olivier or Bruce Willis could manage on stage and screen.
So, on reliability alone, I guess I'd rather be accused of rioting in Amsterdam than of insurance fraud in Tel Aviv.