A person who is exceptionally bad at everything.

Your a Grillbilly when your grill is the nicest thing about your house.

A person who very hard to work with and a fuck-up at almost anything, but thinks he is good. Tends to be vocal but never about his own ability to seemingly always fuck things up.

someone who is good at what he attempts but is conceited and arrogant about his own skills

a person who thinks he knows it all and is not swayed by the facts.