"Fugue for Frog" is a suggested new theme song for The Muppet Show, performed by The Muppet Orchestra backstage in episode 123. Floyd Pepper and the rest of the Electric Mayhem threaten to leave the show because of the "square" theme song.
Kermit allows Floyd to write a new theme song of his own. Later, Floyd presents his new composition for Kermit backstage as "Fugue for Frog". Kermit says he likes the title, but Floyd warns him beforehand, saying he will "hate the rest". Quite so; after having heard the piece, Kermit shouts out, "That was the worst!"
Musically, the piece appears to be a parody of Frank Zappa's most ambitious and exclusive style.