The line comes from Seinfeld, where the Soup Nazi, a strict soup vendor played by Larry Thomas, refuses service to customers who break his ordering rules in the 1995 episode The Soup Nazi. The phrase quickly entered everyday language as a comic way to say no, then found a second life in memes, reaction videos and short-form edits where a single refusal is the whole joke. It endures because the wording is short, instantly recognisable and easy to drop into almost any situation involving a denied request.