Ronnie Kray is best known as one half of the Kray twins, the notorious London gangsters whose story has been retold in films, documentaries and popular culture for decades. That association gives a two-word farewell like be safe an instant gangster-movie flavour, even when it is lifted out of context and dropped into a short online clip. On soundboards it circulates as a compact sign-off rather than a punchline, which is why editors reuse it to close videos, memes and reaction edits with a knowing, old-school toughness.