You know those pads you sign after using a credit card that are supposed to verify your signature? Well, one smart-ass decided to test whether it was really doing anything. Every time he used his card and had to sign, he'd write Xs, squiggly lines, even "Crotchy Crotchington." Nuthin'. The machine had no problems with any of these bogus signatures. Until one day, he met a machine that didn't like what it saw. Curious what that pretty dumb but NSFW signature was? Then read more.
That's right — a penis doodle. The machine promptly spit out a receipt asking the cashier to verify the signer's card with an ID. Now, thanks to one man's juvenile experiment, we know we can't just write anything we want! Thanks, smart-ass man.