[The way I heard it, the quote about the singing horse--or the NOT singing horse--came from Big Bill Broonzy when asked if a song he had just sung was a folk song. Subsequently attributed to everyone and his pet chicken....]

In a production of Shakespeare's "Richard the Third," when the great John Barrymore cried out the famous line, "A horse! A horse! My kingdom for a horse!" this struck one audience member as hilarious and he broke into raucous laughter. Stunned silence in the theater as Barrymore's intense eyes slowly swiveled to gaze up at the place from which the laughter had come. Then he raised his arm, pointed a trembling hand, and intoned, "Or saddle me yon braying ass in the balcony!!"

Don Firth