Taken from the saying "It ain't over until
the fat lady sings," commonly attributed to ex-Yankee ballplayer Yogi Berra.
Presumably, the "fat lady" in question
is a stereotyped opera singer, replete in Wagnerian Rhinemaden
garb. Ironically enough, the "fat lady" was usually singing
the United States National Anthem, the traditional
way to START a baseball game.