In a longstanding tradition of debauchery, drunks, scanty costumes and excrement, the University of Wisconsin and the city of Madison, Wis., brace themselves for yet another Halloween on State Street. Just as moths to the flame are University underclassmen flocking to Madison to experience firsthand the heralded night of escape. This year, however, might bring obstacles to those underage drinkers looking for a riot or the perpetual nip-slip.