I see others have capitalized on this well-known mondegreen. Jon Carroll believes Gladly is the most frequently mentioned of all mondegreens.

It's interesting that a Google search for “gladly-the-cross-i'd-bear” yields over two hundred hits, none of which identifies an actual hymn. All the links are references to the joke and mention a supposed hymn with the title “Gladly The Cross I'd Bear.” My guess is that the oft-quoted mondegreen makes reference to a hymn that doesn't exist by that title but seems as though it should. Masato's reference to the line in “Keep Thou My Way&rdequo; probably quotes the lyrics correctly. My dad probably picked up the joke along with everyone else and enjoyed telling it in the first person.

      - Mark