Of all the TV theme songs that have secret lyrics — lyrics that were never used on the show — I think the best set of lyrics may be the ones for the Andy Griffith Show theme. (Even better than “The X-Files is a show/With music by Mark Snow.”) The words were supplied by the veteran actor Everett Sloane, best known as the guy who gets the best speech in Citizen Kane, and while they were never sung on the show, Griffith recorded them. (One of the main reasons for writing lyrics to an instrumental theme was, of course, so that that vocalists could record them, or the star of the show could include them on an album.) They fit the atmosphere and style of the show so perfectly that they actually enhance the theme music by telling us more of what it’s about, instead of sounding redundant like many theme song lyrics.
On the other hand, if you want to hear “secret” lyrics that are completely inappropriate for the music, try these lyrics for the Hawaii 5-0 theme song recorded by Sammy Davis Jr. (Via Lee Goldberg)