A sellner
A skinny, tall nobody who thinks they're the most popular person ever and talks to themselves like they're in a group chat and can't tell the difference between someone who says 'hi' and someone who actually likes them.
'Hey, Sarah! How's your day?', but Sarah doesn't exist.
'We're besties forever!', after I said 'hi' once.
'I'm so popular!', while no one even came to their party.