Coonass is a pejorative that Cajuns from Louisiana received during WWII when they were asked to be translators for the French resistance. The language in Louisiana diverged into cajun French and Kouri Vini (creole French) over the 200 years since Louisiana was first colonized, so modern French didn't line up and there was still a bit of a language barrier. The French called these people connasse, which basically means stupid because of this, but the cajuns took it as a kind-hearted nickname and brought it back home with them. Many cajuns were and still are upset that the term is ever still used to refer to them because it's a coarse word they feel belittles their culture, so if you're in the company of them and you don't know how they'll react, you might want to wait until they bring it up.

I love this site, this is the second thing about louisiana culture i've learned in the past month by asking a question like this. The other one was that Cajun is derived from Acadian.

And i got to share that "creole" has many meanings, including the stuff that forms on the inside of a BBQ itself.