The April Fool is a character featured in the Nickelodeon animated series The Fairly OddParents. He is the mascot for April Fool's Day and has a tendency to play very mean pranks on people. His nasal voice and trademark punchline, "What's up with that?", are modeled after comedian Jerry Seinfeld.
The April Fool made his first appearance on the show in the series' first Christmas episode, "Christmas Every Day!" In the special, as a result of Timmy Turner's wish to have Christmas every day, he joined up with the Easter Bunny, Baby New Year, and Cupid to eliminate Santa Claus and end Christmas.
The April Fool would later get an episode of the show based around his holiday - "Fool's Day Out".