Of course it works.. jeezus.. what young male isn't going to slow down to ' observe' topless blonde babes no matter what sign they're waving about? [ though I suspect a few will drive into trees, light stands and mail boxes craning their necks to keep looking ]
as for wimmen and gays straining to view guys with their tackle out waving signs...well...
Oddly... living in Denmark... I haven't seen this campaign...
But I'm just off for a drive now!
(Truth be known... cars here cost 2Â½ times what you pay in UK... youngsters can only afford cars that should be on the scrap-heap... on the negative - no aibags or brakes... on the positive there are relatively few other cars on the roads to smash into - up here in the North you are unlikely to be within visual range of 3 other cars on the motorway)
As an aside... when I first came to Denmark, there were no scrupels about pornography (and you'll still see a complete nude in every edition of the equivalent of the Radio Times). I remember walking up to a kiosk counter to see a magasine called "Teenage Fcuk #2" at knee height in front of the counter. I begged my missus to be allowed to buy it (to slip into the magazine rack in the mess) but proptly got warning No1.
Danish girls... you've got to love 'em... they'll take anyone home on a Saturday night rather than go home empty handed.