Heathcliff Surprise / The Big Break In

S1 E55: It's Heathcliff's birthday, and he's a very happy cat. That is, until he realizes all his friends have forgotten! Everywhere he goes, cats and people blithely tell him they're busy, and send him away. Angry and hurt, Heathcliff decides to run away. When he goes into the Nutmeg home to get his things, everyone is there yelling "SURPRISE!!" / A lady moves into the neighborhood that has twelve gorgeous female cats. Heathcliff, Riff Raff, Hector and Mungo try several plans to break into the house and meet the new felines, but only our hero succeeds. However, once inside, Heathcliff discovers that a harem is more than he had bargained for, and makes his escape.