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I know this is a bit old, but i believe it's one of the best guerrilla ads that have been done... In the summer months, Playboy Magazine was looking for a new Playmate among the girls on the beach. They organized a competition with juries that had to select the future covergirl for the magazine. Just to encourage the girls to participate in the competition, they decided to give them a beach towel, where the girls could lie on and sunbath, looking like they were on the front magazine's page. Very good thinking, to brake the ice, and start thinking of it as a game... helped girls loosen up.

Source: advert-eyes