jacklegged
A dummy who thinks they're better than they are. They’re one step away from being a total jackass and have no idea how close they are.
My brother is a jacklegged. He thinks he’s the best at video games but can’t beat me.
My crush is a jacklegged. He asked me out and then forgot my name.
My dog is a jacklegged. He barks at the mailman and then eats my homework.