Food and the dead, Irish begging door-to-door, Tim Burton’s “Nightmare Before Christmas,” Michael Jackson’s “Thriller” — Halloween, an event now celebrated in many parts of the world, has come to mean different things to different people. For adults, the holiday has acquired a Mardi-Gras flavor and offers opportunities to pose at parties and bars as preening pimps and naughty nurses. Spandex, it seems, has liberated many…