Fergie is a nickname British popular newspapers use for two different famous people called Ferguson. One is Sarah Ferguson, who married into the royal family and became Duchess of York. The other is Sir Alex Ferguson, who managed Manchester United football club for many years. The “-ie” ending makes a familiar short name, the way Charlie comes from Charles. Which Fergie someone means depends on whether the story is royal gossip or football. It is tabloid English — friendly, a bit cheeky — not what you would write in a school essay. Though actually, plenty of ordinary families also nickname a Ferguson “Fergie”; the papers just made two of them famous.