"Mad, Mad, Mad, Mad Hatter" is a song sung by Grover (as The Mad Hatter) in Abby in Wonderland. In the song, he explains how a hat can change how one feels and uses examples of his own hats. He gets mad when he wears a hat that doesn't fit, he gets sad when he wears his broken beanie cap and he gets glad when he wears a hat made up of fruit.