Prostitution is legal in Denmark.
"Copenhagen Mayor Ritt Bjerregaard sent postcards to city hotels warning summit guests not to patronize Danish sex workers during the upcoming conference. Now, the prostitutes have struck back, offering free sex to anyone who produces one of the warnings."
Actually, I suspect the Mayor's true reason for requesting restraint from reprobates is that the more money into prostitutes' purses means less money in politicians' pockets.
But I'm just jaded that way...