I'd venture to say
Jungle wa Itsumo Hale noche Guu is one of the funniest things I've ever watched. Hale (age 10) lives with his dissolute mother Weda in a small jungle village populated by some very strange people. (The village chief is especially hilarious.) One day Weda discovers a girl named Guu who's about Hale's age and adopts her. Turns out Guu is not really just your ordinary cute, nice girl. Guu's voice actress, Watanabe Naoko, gives one of the finest comic performances I've ever heard. All you really need to know about Guu is this:
Watch the first three or four episodes. You'll know by then if you want to watch any more.