Greenlighters: underground sex movement

"Greenlighters are an emerging underground movement of sexually promiscuous teenagers, including bisexual, homosexual, and heterosexual members. Members of this movement wear a green polo shirt with the collar up, indicating that they are open to pretty much any sexual adventure. When someone comes up to them and puts the collar down, they are "collared" and will go with that person and do whatever sexual act they ask. Transfer of money is not usually involved. Some parent groups are starting to get involved - urging parents to go through their kids clothes and confiscate green shirts and polos."
Source: Metafilter