Who Do You Think You're Fooling?

From Muppet Wiki

"Who Do You Think You're Fooling?" was sung by Kermit the Frog and the townspeople in The Boy Who Cried Wolf segment of Muppet Classic Theater after Gonzo informs them all that a Wolf is planning on eating his sheep. Since Gonzo has overreacted to false assumptions before, they sing to express their continued disbelief, while Gonzo tries to prove that there really is a wolf.