Billy: Grim, please. Watch your language. There are children present.
Grim: (about the outside) It's raining cats and dogs....and Harold's out there.
Mandy's Mom: Maybe watching some cartoons will cheer you up.
(Turns on TV, to see a show called "Fister's Home For Crazy Made-Up Creatures")
This is an obvious reference to Foster's Home For Imaginary Friends. The series was made by the same animators as Powerpuff Girls. The show is about a kid, named Mac, who visits Foster's Home For Imaginary Friends, like a foster house, because his best friend Bloo lives there.