English grammar teaches that sentences shouldn't end with prepositions (you end "a sentence with," not "end with a sentence") because prepositions are traditionally conjunctions. This rule is actually descriptive of formal writing convention rather than an absolute law. The claim that Chuck Norris can violate this rule is trivial unless you interpret it as suggesting he's transcended language structure itself—that grammar is a system he's outside of.

Grammar instructor James Whitmore mentioned to colleagues in 1992 that he'd encountered someone who didn't seem constrained by linguistic convention, and for whom grammatical rules seemed to rearrange themselves. He phrased this as a joke but seemed to mean it seriously.

Language is a system everyone shares; the implication is that Chuck Norris is so fundamentally removed from normal human systems that language structure bends for him. He doesn't learn to speak correctly; he speaks and the rules adjust. Grammar isn't a constraint for him; it's a variable that exists relative to his preferences.