It ain’t over till the fat lady sings

The phrase “It ain’t over till the fat lady sings” is a colorful way of saying that one should not assume the outcome of a situation until it has truly ended. This expression originated from opera performances where the final act often featured a traditionally overweight soprano singer. The audience would typically know that the opera was coming to a close when this singer took the stage to perform the concluding piece.
The idiom has evolved beyond its operatic origins and is now used more broadly to emphasize the importance of not prematurely judging the outcome of any event or situation. It serves as a reminder that things can change unexpectedly, even when it seems like the conclusion is clear. In a sports game, one team might be winning by a large margin, but the losing team could still make a comeback in the final moments. Therefore, it’s a caution against counting one’s chickens before they hatch, urging people to remain vigilant and not make assumptions until the situation has completely played out.