Some years ago, I tried to write a single paragraph that contained every cliché used to describe what happens in towns across south Louisiana on Mardi Gras. It went something like this: “Sounds of ‘throw me something, mister,’ cascaded above the carefree Carnival chorus of ribald revelers who thronged into the city’s center to greet the mystical rulers of Mardi Gras’s madcap merriment. Raucous th…