know nothing know it all

A person who knows nothing about most topics they chime in on in conversation. This person will be 16 years old with zero experience about farming and tell a farmer about crop rotation. This person will tell a European car technician what's wrong with their car, refuse to pay diagnosis, because they used to work at Chevy in the 80s, and then bitches when the car isn't fixed.

Rather than listening and increasing their knowledge they insist to run their mouth to the point where everybody is annoyed.