The Angry Beavers - Season 3 Episode 8 Sang 'Em High

Dag concedes that he can't win an argument against Norb. Dejected at the pond, he stumbles upon Laverta Lutz, the "magical, mystical, Lady of the Lanes." Laverta grants Daggett a wish. His wish is to leave Norbert speechless in an argument. Laverta tells Daggett that "the argument is not over until the fat beaver sings." Not knowing exactly what that means, Dag rushes back to the dam to battle it out with Norb. Just as he had wished, he leaves Norbert speechles when in the throws of battle, Dag turns into a fat, over-sized beaver who sings his arguments like a professional lounge singer.