There are a few different thoughts as to the orgins of the term coonass as it refers to Louisiana Cajuns.  Some have said that it compares the Cajun to the part of the raccoon under the tail being the lowest part of the animal.  Others claimed that since a Cajun was lower than a black man, and a black man was refered to as a "coon", then a Cajun would be the coon's ass.  Most likely the orgins of the term coonass are from a French word used in the 1940's as a slang for a very stupid person.
During World War II the U.S Army was in need of French interpreters.  The young soldiers from the Louisiana bayous were found to be a good source for this since being of French decent, they already knew how to speak the language.   These young Cajun boys were assigned as interpreters for high ranking American, British, and French officiers.  The French officiers would recieve their orders from the American staff officiers running the war effort in Europe through these young, often uneducated, low-ranking boys who couldn't even speak proper French.  This was considered a major insault to the dignified French officiers.  They started calling the young interpreters from Louisiana the French word CONASSE (coo - nass)

In time the French troops in Europe refered to all interpreters, even those not from Louisiana, as a conasse.  Other American and British soldiers, not knowing any better, started calling the interpreters the dergatory word they heard as "coonass".
The term coonass may have died out if it were not for the Louisiana oil boom.  Many oil field workers from Texas and some from other states, who served in Europe during World War II, remembered the Louisiana soldiers being called "coonass".  They started calling the Cajuns coonass and at first thought working in Louisiana would be an unpleasant experience.  They soon learned that the Louisiana Cajuns were not at all stupid, that they were a hard working, fun loving bunch of folks, and boy can they cook.
Understandably, the derogatory term coonass is still considered offensive to many Cajuns of South Louisiana.  Most others have made  coonass a endearing term for this fun loving group of people and their culture.  Many South Louisiana people proudly refer to themselves as a coonass.  Bumper stickers with "Registered Coonass" and "I'm a Coonass, me" can be seen on vehicles in South Louisiana.  Coonass cooking and recipes are enjoyed all over the country.   It seems like now where ever you go, people want to be included as a coonass and want to have a coonass cook or plan a fun event for them.  Just get you a good bowl of Jambalaya and join the fun!