Riddle Number Thirteen

A poor man was sitting next to a rich man on a park bench. They were complete strangers. The poor man says to the rich man, "I bet you all the money in your wallet that I can sing you a song with any lady's name of your choosing in it. A real song, that's legitimate." So the rich guy agreed. "How about my daughter's name, Joanna Armstrong Miller?" he said. The poor man sang a song and the rich man gave him all the money in his wallet. What song did the poor guy sing?