nacademic
A person who talks big about knowing stuff, but can't back it up with anything but hot air and a bad grade.
My bio teacher is a nacademic. He says he studied dinosaurs, but he can't even remember what a T-Rex eats.
She claims she's a math genius, but she can't do long division without crying.
He says he's a history expert, but he thinks the Civil War happened in the 1900s.