A Weevilton
A Weevilton is a person who thinks they're perfect and everyone else is a waste of oxygen.
You: I did my math homework. Weevilton: You're still wrong. You're just lucky I don't fail you.
DM: 'You think you're cool? I'm the only one who matters.'
In class: Weevilton says the answer is 42. Teacher says it's 42. Weevilton says, 'See? I was right.'