Plaquemines Parish. Just two syllables- Plak-mean, no strong accent on either syllable, but slightly more on the second. The name comes from a bayou, and is thought to mean 'persimmon,' but no certainty to this interpretation.
Speculation continues here as to what Aaron Neville sang, but that is pointless until someone posts the words. Louisianans who know the history of the Huey Long days know the song and would expect 'cracker.'
Cracker is one of those appelations that is demeaning mainly in certain contexts. It often shows up in stories about the political differences between the rural population of northern Louisiana and the New Orleans city folk. Don't use unless you know your audience and how to use it.