"The Grouch Anthem" is Oscar's opening song in Follow That Bird. Oscar sings the song in front of a giant American flag as a spoof of Patton. In the middle of the song Oscar is joined by a chorus of humming Grouches. After both verses have been sung, Oscar delivers a soliloquy with Grouches singing in the background.
In keeping with the contrarian nature of Grouches, Oscar insists that people stay sitting down for the Grouch Anthem, instead of rising to attention as with the national anthems of most countries.
Oscar considers the anthem the "best part" of the movie. And tells the audience to "have a rotten time" watching the movie.