The Grim Adventures of Billy & Mandy

The Good, the Bad and the Toothless (3x31)

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When Billy has a loose tooth he can't wait for the Tooth Fairy to appear to give him money. Then, Mandy, who doesn't believe in the Tooth Fairy, asks Sperg to end Billy's waiting by knocking his tooth off. However, Sperg's punch leaves Billy unconscious, who then has a dream about being in the wild west, where the Tooth Fairy has taken his tooth. Then, Mandy challenges the Tooth Fairy to a showdown to recover the tooth, and she comes out victorious just as Billy awakens. In the end, Billy does find money under his pillow, while the aged Tooth Fairy watches through the window.