To add to Bot's answer:

Coonass is an epithet used in reference to a person of Cajun ethnicity.

Although some Cajuns use the word in regard to themselves, other Cajuns view the term as an ethnic slur against the Cajun people, especially when used by non-Cajuns.

Socioeconomic factors appear to influence how Cajuns are likely to view the term: working-class Cajuns tend to regard the word "coonass" as a badge of ethnic pride; whereas middle- and upper-class Cajuns are more likely to regard the term as insulting or degrading, even when used by fellow Cajuns in reference to themselves.

Despite an effort by Cajun activists to stamp out the term, it can be found on T-shirts, hats, and bumperstickers throughout Acadiana, the 22-parish Cajun homeland in south Louisiana.


Etymology
The origins of "coonass" are obscure, and Cajuns have put forth several folk etymologies in an effort to explain the word's origin. Some believe that the word refers to the Cajuns' occasional habit of eating raccoons, or from the use of coonskin caps by the Cajuns' ancestors while fighting in the Battle of New Orleans or in the Revolutionary War under Spanish colonial Governor Bernardo de Galvez. Others attribute the term to the racial slur "coon," used in reference to African-Americans — thus implying that Cajuns are lower than African-Americans in social standing. Yet others hold that the term derives from the shape of Cajun women after having children (like a raccoon viewed from above).

The most popular folk etymology, however, stems from late Louisiana congressman and cultural activist James "Jimmy" Domengeaux, who maintained that "coonass" derived from the continental French word "connasse," which he contended meant "stupid person" or "a prostitute without health papers" (dirty prostitute). He asserted that Frenchmen used the term in reference to Cajun soldiers serving in France during World War II, and that Anglo-American soldiers overheard the term, transformed it into "coonass," and brought it back to the U.S. as a disparaging term for Cajuns. Citing Domengeaux's etymology, Louisiana legislators passed a concurrent resolution in the 1980s condemning the word. (Contrary to popular belief, the lawmakers did not ban the term.)

Research has since disproved Domengeaux's "conasse" etymology. Indeed, photographic evidence indicates that the Cajuns themselves used the term prior to the period in which "conasse" allegedly morphed into "coonass." As a result, the origin of "coonass" remains uncertain.


Miscellanea
Cajun governor of Louisiana Edwin Edwards often used the word "coonass" in reference to himself and other Cajuns.
In the early 1980s, a Cajun worker sued his former employer over repeated use of the word "coonass" in the workplace. The lawsuit led directly to the federal government's recognition of the Cajuns as a national ethnic group as protected by the Civil Rights Act of 1964.
While campaigning for President in Louisiana, Ronald Reagan once suggested his own appointment as an "honorary Cajun coonass."

Sources
Acadian and Cajun Genealogy and History
Encyclopedia of Cajun Culture
Jules Gilpatrick, 1965 LSU Graduate, freeflyte@centurytel.net.
Shane K. Bernard. The Cajuns: Americanization of a People (Jackson: University of Mississippi Press, 2003).







By the way, my wife is 1/2 coonass and doesn't find the term offensive. Or maybe she just ignores me as usual and doesn't know I use it