The Danish tax authority has found guerrilla advertising, or rather old-fashioned bulletin board systems, a great place to lure tax evaders out of the woodworks.
"Wanna make some extra cash?" asks the ad posted on public bulletin boards everywhere, complete with a tear-away phone number. "you can make up to 150 an hour, black* (tax free) call me at 80 60 18 92 to find out more. Peter K." People who call the phone number are then greeted by a recorded scenario, first a mans voice who says "So you've seen our job ad. 150 an hour, tax free. But won't tell anyone if you won't..." the man is interrupted in his spiel by a surprise visit from the tax authority entering his office and then there's a woman's voice on the line "Hello, this is from the tax authority. You're not working 'black' are you?" Imagine if everyone did that!" the woman threatens at the end "you should be happy he doesn't have caller ID." So far over a thousand Danish people have called the phone number.

The campaign will continue in more traditional media such as cinema, posters and radio, so only a small part of their expensive advertising campaign is leeching on the free public bulletin board systems meant for private citizens who can't afford to buy other media space. Imagine if everyone did that!

* In Danish, taxed money is white, untaxed money is black. Everyone is in the red.