Cow and Chicken - Season 4 Episode 14 Monster in the Closet
Overview: Cow wakes up in the middle of the night and finds a monster in the closet. Mr. Monster is actually quite friendly, and the next day, Cow treats him to a grand day out. They enjoy jumping ropes, eating ice cream, and watching TV. But when Mom and Dad discover this, they freak out, and have Cow banish Mr. Monster in the closet forever.