Lacking OF
When you're so empty inside you could be used as a punchbag and you're being a smug, mean, and crazy person about it.
My cousin thinks he's the king of the world because he got a B in math. He’s lacking of and it’s annoying.
My mom is lacking of and she thinks she’s the queen of the universe.
My brother is lacking of and he still thinks he can beat me at Mario Kart.