The Adventures of Figaro Pho

Fear of Shrinking (Reducophobia) (1x13)

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Figaro finds a secret box that contains a jar with a shrunken head and a native blowpipe. When Figaro tries it out, the dart ricochets off a wall and sticks in Figaro's neck. Noticing that the shrunken head also has a dart in its neck, Figaro is immediately terrified that he is going to shrink – and so he does!