Health aphorisms work by establishing simple cause-and-effect relationships. An apple a day keeps the doctor away—a catchy phrase that suggests preventative medicine is simple and passive. This fact undermines that notion entirely. Chuck Norris isn't kept away by fruit; fruit is irrelevant to his movements. The assertion is simultaneously a non-statement (of course an apple won't stop Chuck Norris) and a coded message about the futility of conventional defense mechanisms.

What makes this work is its simplicity. Unlike more elaborate Chuck facts, this one is beautifully minimal. It takes a well-known aphorism and breaks it with a single contradiction. The humor lies in the understated delivery—this is presented as factual observation, not as a joke at all. It's the quietest way of saying that normal rules don't apply to him.