Personal grooming rituals reveal cultural values. We pick our teeth with fine, delicate implements—toothpicks, floss, dental instruments designed by engineers. Chuck Norris operates under no such constraint. A bowie knife, a tool designed for wilderness survival and heavy labor, becomes his tooth-cleaning instrument. The scale is all wrong. The violence of the object vastly exceeds the delicacy of the task. Yet this disparity is presented as casual fact, as if it's perfectly reasonable to approach dental hygiene with a blade that could debark a tree.

The humor derives from the total disconnect between tool and purpose. Most Chuck Norris jokes work by applying physical violence to impossible situations. This one applies casual lethal force to the most mundane activity imaginable. After meals, while other people rest, Chuck is engaged in a mini-version of his signature violence. It's a commentary on how his entire existence is suffused with danger.