Labelist
A labelist is a person who throws labels everywhere like they're going out of style, just to avoid looking dumb when someone asks why they're so sure.
'You're a drama queen!' I said, even though I didn't know what a drama queen was.
'You're a failure!' he yelled, even though he failed the test too.
She called me a 'crybaby' because I cried when the dog ran away.