A Sweeper
A person who's a total brain-dead idiot. They don't know what's going on and they act like they're the smartest person in the room.
My cousin is a total numty-tard. He thinks he’s the best at everything.
That guy in class is a numty-tard. He didn’t even know what the question was about.
The numty-tard next to me spilled his drink on me. I wanted to kill him.