o'practical
A person who acts like they’re the smartest person in the room, but they’re just loud and wrong.
He yelled at the teacher for 10 minutes about how ‘2+2 is 5’ and nobody dared to correct him.
She argued with the waiter about the bill for 20 minutes, even though it was right.
He said he was the best at everything, but he couldn’t even tie his shoes properly.