In the 1970s, I was a fan of Martin Mull’s work, from his TV appearances (“Mary Hartman, Mary Hartman,” “Fernwood Tonight,” “Roseanne”) to his movie roles (“FM,” “Serial”) to his concert performances, in which he always had living room furniture on stage to make himself more comfortable. I lost track of him in the intervening decades, but was happy to hear him this week in conversation on Marc Maron’s “WTF” podcast, in which Mull revealed something I never knew.

In 1969, Johnny Cash had a hit with “A Boy Named Sue,” a novelty song written by Shel Silverstein. When Mull heard it, he laughed and started jotting down some ideas for an “answer song.” The result was “A Girl Named Johnny Cash.” Mull says he recorded it and it became a minor hit, but I can’t find it. However, a singer named Jane Morgan recorded it in Nashville with Chet Atkins and Ronny Light producing, and that version is online…