A Weevilton
A Weevilton is a person who thinks they're the smartest and everyone else is a dumbass.
You: I got 80% on the quiz. Weevilton: You're still a failure. I got 100%.
DM: 'You didn't study. You're just lazy.'
In class: Weevilton says the answer is 22. Teacher says 22. Weevilton says, 'I knew it.'