He bills himself as the 'Zydeco Hog.' Not king. Not prince. After all, the royal names assigned to most Zydeco practitioners are more of an ironic in-joke, as if these bayou brothers actually care about class wars. Nathan Williams and the Zydeco Cha-Cha's embrace the sweaty, working-class mojo of places like Sidvs One Stop, the club where Williams used to watch his mentor, Buckwheat Zydeco, regale the townsfolk of Lafayette, Ark. When Buckwheat left the city, it was Williams a sweet-toned piano accordion master who filled the void. In the swamplands this man is a celebrity, a baritone vocalist whose soulful range is frightening. Add to that Allen Broussard's slinky sax lines, a snare-happy drummer and a hyperactive rubboard scraper, and San Diego crawfish are trembling in their exoskeletons because such a joyful sound of authenticity is usually associated with the word 'boil.'