Trick or Treat? It's always a treat to celebrate Halloween with everyone's favorite Nickelodeon friends as they discover candy, costumes, and haunted happenings! This year, celebrate Halloween with Dora, Diego, the Wonder Pets, Yo Gabba Gabba, Blue's Clues, and Kai-lan.

At head of title: Nickelodeon. At head of title: Nickelodeon.

Dora the explorer: "Boo" -- Go, Diego, go!: "Freddie the fruit bat saves Halloween" -- Wonder Pets!: "Save the bat" ; " Save the donkey" -- Yo gabba gabba!: "Halloween" -- Blue's clues: "What is Blue afraid of?"-- Ni Hao, Kai-lan: "Ni Hao, Halloween.".