FABNERD
A FABNERD is someone who thinks they're cool but is just average at everything.
My friend is a FABNERD. He thinks he's the best at basketball but he can't even shoot straight.
My brother is a FABNERD. He failed his history test but still claims he's the smartest.
My neighbor is a FABNERD. He thinks he's a rockstar but he can't even play guitar.