Blondie guitarist Chris Stein wrote this to cheer up Debbie Harry. She was down as her gray cat named Sunday Man had run away whilst they were away on tour.
Though never released as a single in the United States, the song was a #1 hit in the United Kingdom and in Australia. In Britain the sales were boosted by another previously unavailable track on the B-side: a French language version of "Sunday Girl."
The song was covered in 2013 by the band She & Him on the album Volume 3.