"The Cat Came Back" was sung by Rowlf in The Muppet Show episode 523. Gaffer, in one of his few onstage appearances, played the titular cat opposite his owner Benny. Among the many dogs who appeared in this number were Rover Joe, Wolfhound, and Baskerville.
The song is a popular children's and folk tune which has evolved from a minstrel number of the same name written by Harry S. Miller in 1893. Multiple versions with a wide variety of verses can be found.