1. A smart person, usually from a rural area, the south or small town; who deliberately speaks or behaves in a manner that indicates a lack of understanding of the modern world and uses this false impression to gain advantage of urban or cosmopolitan people, i.e. asking for favors, borrowing money, borrowing cars, or even moving in (rent free of course).
2. Person who uses a false impression of naiveté to prevent being taken advantage of by "City Slickers"
1. That Country Dumb girlfriend of his said, "Oh this insurance stuff is all so expensive and complicated! Can ya'll borrow me the five hundred dollar down payment, so's I can get my teeth fixed".
2. Quoted from the movie "Ray"
Ahmet Ertegun: You could have fooled me.
Ray Charles: Well, I gotta keep my eye on you city boys. Back home they call it Country Dumb.