S1·E103 Heathcliff Reforms

Hector, Wordsworth and Mungo decide to teach Heathcliff a lesson after a typical day of being picked on. That night when Heathcliff is fast asleep, the cats sneak into his house, and with Hector dressed like a ghost, frighten Heathcliff into promising to be nice to his friends. After a few days of being good, Heathcliff finally catches on and puts his sneaky friends back in their place.