Where Did The Term Coona** Originate?

On a recent trip to Colorado a TSA attendant, who was from Lake Charles, Louisiana, asked my family and me if we were "Rednecks" or "Coona**es"?  We replied, "Cajuns".

What does "Coona**" mean?  And where did it originate?  And is it insulting?

The origin of the word is a bit complicated and whether or not it's offensive differs from one individual to another.

The word "Coona**" has been banned from all broadcast and print media.  But why?