I hate to be "that person", but you have GOT to watch this show while under the influence of certain soon-to-be-legal substances. atLEAST once. Cons: sometimes you forget it's supposed to be a children's show.
Hilarious for people of all ages, one of the few really good kids' cartoons on these days. The episodes are wonderfully random, and the animation is mildly deranged, but it just adds to the humor. Cons: Might be a bit too mathematical for really young children.