Mac and Bloo meet residents Eduardo, Wilt and Coco, and the home's staff.
Foster's Home for Imaginary Friends
Season 1 Episode 5: The Trouble with Scribbles
Bloo discovers a door in Foster's that everyone is forbidden to open, and nobody tells him what's behind it. One night he opens it, and releases Scribbles, a friend that does jobs around the house and causes everyone to become lazy.