Trustafarian is so old round here (NW/UK) it can hardly even be considered slang. We Mancs use it to describe the wealthy crusties that hang around squat parties taking more drugs than can possibly be any fun and alternating between telling oh so amusing stories about their servants and earnestly banging on about how money is the root of all evil. They are generally the loudest dirtiest girl at the party that somehow can always afford a taxi home.