The movement is sending shock waves through the normally orderly world of Berlin estate agents: when they show off apartments for rent, their presumed tenants strip off and prance around wearing nothing but Mickey Mouse masks to hide their identities.
The protesters, who paint their naked bodies with slogans such as "too expensive" and "rip off", pose as ordinary would-be tenants and queue up to "view" expensive apartments to let.
Once inside they strip off and dance around to blaring music pumped through loudspeakers while being filmed. In most cases they manage to flee before the police arrive. A video of their protest usually appears on YouTube the following day.
"We want every estate agent and every apartment management company to be aware that if they try to rent out flats at rip-off prices, they can expect a visit from us," one of the protesters, who would only identify himself as Denis, declared on one of the videos.
The rent rise protest is conducted by a group called Hedonistic International which recently gained publicity after its members stormed a neo-Nazi pub. Their demonstrations have so far been confined to the Berlin inner-city districts of Kreuzberg and Freidrichshain. Both districts are being gentrified after providing cheap flats for immigrants and students for more than two decades.
"We did not want to go on demos where everyone is either angry or sad, we wanted to do something that says yes to life," another of the naked protesters called Peter told Der Spiegel magazine. "We want to shock in order to get our political message across."
While some estate agents have resorted to calling the police and tried to bring charges against the protesters, Andreas Stücke, of Germany's estate agents' umbrella organisation Haus und Grund Deutschland remains unruffled. "Those who enjoy stripping off on such occasions should get on with it," he said, dismissing the protests as a passing "hip" fad.
The Berlin protesters admit to being inspired by anti-rent activists in Hamburg and Paris where similar demonstrations have been held. But by the standards of both cities, not to mention Munich and London, Berlin's rent levels are minimal. Although the rent for a very well appointed apartment in one of the capital's more fashionable inner-city districts can occasionally reach up to €1,000 a month, the current average for a two bedroom flat in these areas is €640 a month.
"Berlin's tenants are spoiled," argues David Eberhart of the accommodation group which controls 40 per cent of the city's rented homes.
He points out that compared to the comparatively wealthy city of Munich, where tenants spend an average of 17.6 per cent of their income on rent, in Berlin the average is only 12.3 per cent. He maintains that as much of the rent increases are a result of making uninhabitable property habitable, the rises are in everyone's interest.
However, the protests appear to have alarmed Berlin's Social Democrat and reform communist Left Party government headed by Klaus Wowereit, the socialist mayor who coined the term "poor but sexy" for the capital. His administration has just launched an initiative aimed at capping rents in the city's gentrified inner-city boroughs.
* If some cyclists feel vulnerable without a helmet, they should spare a thought for participants in the World Naked Bike Ride, an annual event designed to draw attention to just how risky it can be to cycle in the city. More than 1,100 people took part in the London event this year, one of dozens in 19 countries involved.
* 24 women assembled at California's Venice Beach earlier this year for a topless march – while their male companions wore bikini tops. The GoTopless campaigners want women to have the same right to be bare-chested in public places that men do.
* Old-fashioned nudists in Languedoc, home of Europe's most enduring "naked city", have had their idyll disrupted by an influx of swingers. The nudists complain that the swingers, who come to visit new partner-swapping clubs and raunchy hotels, are making people think that the two activities are one and the same.
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