heard on LBC radio yesterday.... someone asked for an explanation of the saying "Its not over till the fat lady sings" best answer was.......
In the US elections the last state to sign in with their results is Texas, now the state of Texas is known affectionately as "The Fat Lady" so their results are very important indeed hence the expression "Its not over till the fat lady sings"----- true or not ?
I've always been led to believe it was associated with American Baseball when a 'lady' sang, likely the Anthem, at the end of a game, hence 'it aint over until the fat lady sings'.
This may be an urban myth, likely is, but that has always been my 'take' on the expression.