Melt, a grilled cheese restaurant in Cleveland, offers 30% off for life in exchange for getting a grilled cheese sandwich + logo (scull and crossbones) tattooed on one's self. I met a woman at the airport who had a sleeve of food-related tattoos including a Melt one. In addition to the discount, these ambassadors (my term) are treated well -- invited to special parties, restaurant openings, etc. It's a great scheme because it's strong social proof to others that Melt is a trendy/cool/worthwhile/whatever place. Being on the Food Network all the time can't hurt either.