The name refers to Reggie Kray, one half of London's notorious Kray twins who ran the East End underworld in the 1960s and became lasting British crime folklore through films and documentaries. Short, aggressive quotes attributed to him circulate on soundboards as instant tough-guy reactions, with this two-word dismissal among the bluntest. Because it is under a second long and needs no context, meme editors lift it for comedic shut-downs. Its appeal endures as shorthand for no-nonsense East End menace in a single breath.