when the fat lady sings

When the fat lady sings, the show's about to begin.

The saying also means that "it's all over" when the fat lady sings.

"It ain't even over when the fat lady sings.

"We've sacrificed immediate gains to fuel our expansion, but when the fat lady sings, we'll win," he said.

"When the Fat Lady Sings"

Mr. Jackson said Dr. Dean's supporters on Capitol Hill "will wait for the governor to make the decision about when the fat lady sings."

Murder, She Wrote (1984) playing "Howard" in episode: "When the Fat Lady Sings" (episode # 6.8) 11/19/1989

2000: GZA & DJ Muggs - When The Fat Lady Sings

As Götterdämmerung is about the end of the world (or at least the world of the Norse gods), in a very significant way "it is [all] over when the fat lady sings."