Forty minutes before a Red Bulls game, some of the craziest sports fans in the New York area meet at the corner of Market and Jackson streets in Newark. There are hundreds of them, most of whom have been singing for three or four hours in the bars near the stadium. They don't look the same. They aren't from the same places, but they live by the same edict: Do. Not. Stop. Singing.

These are the inhabitants of the "South Ward" of Red Bull Arena, a three-section area made up of three groups—the Empire Supporters Club, the Garden...