Simon & Simon

The theme song to "Simon & Simon" changed after the first season. The song in the first season had a sound I can only describe as "An American in Tijuana." The replacement theme song had a snappier rhythm, more like "Zany Times in San Diego-- Er, Los Angeles." The theme music was played at the beginning and end of each episode. At the end of the final episode for the first season, some guy actually sang lyrics, which he probably had written, to the music. I don't remember the lyrics, but there was something along the lines of "'cuz they're brothers." First and only time I've ever seen that happen on a TV show. The original theme song didn't entirely vanish. It continued to be used as a lead-in between the end of the new song and the "brought to you by..." commercial intro.