Dingus McLingus

An individual with no aptitude for success who nonetheless presume competence. AKA, a skill-devoid mansplaining rube who is the unwitting object of ridicule over an extended period of time (for instance, their adulthood). AKA, a haughty knave, lacking in cunning and sophistication, who is ineffective in all pursuits, much to the irritation or amusement of his or her peer group. Usually male.

Don't let Dingus McLingus walk the dog. He'll probably let it get eaten by a hawk.