oblivisumption
A dumb belief that you're the only one who's clueless and everyone else is doing things your way, even if you're the one who forgot to bring a drink to a bar and still think it's okay.
"I didn't bring a drink, why are you all drinking?", said by someone who thinks showing up is the same as contributing to the party.
"I left the concert early, why are you still dancing?", said by someone who thinks walking out is the same as being cool.
"I texted you in all caps, why are you still talking normally?", said by someone who thinks shouting is the same as speaking."