This is from BevJoe (McGuire), no blarney.

An Irishman named O’Leary, who loved to sing as he worked, bought a mule to farm his garden. The mule worked well, but was almost totally deaf. So, when his owner yelled, “Whoa!”, the animal often continued plowing. Asked how the mule was working out, O’Leary shook his head. “There was a time,” he said, “when all that the neighbors could hear was me singing my lilting melodies. Lately, I’m afraid, they’ve heard nothing but my riled Irish whoa’s!”