666 The number of the devil according to Revelations 13. Made known to many people after the film "The Omen" was released. Also in hebrew every number had a subsequent letter and 6 = w therefore some people believe that the internet is the Devils tool.
Some &&GOOOFFFIIIKKK__SLIYMYFUCKINGWRISTS__X kids write it EVERYWHERE to appear cool when really thay appear stupid and amazingly silly as they probably go to church with their mum every Sunday
Friend: Hey, see that kid with the 666 on its backback, jumper, trousers and forehead?