Anime director Masaaki Yuasa (The Tatami Galaxy, Kaiba) will be making an episode of Adventure Time for the upcoming sixth season - and they've already released a clip from the episode. Naturally, it's extremely weird - although Adventure Time is already a pretty weird show on its own before an outsider who primarily works in anime takes over.
The real interesting thing is that the normal creative team specifically gave no creative input to the episode, allowing Yuasa total control - so he wrote, directed, and storyboarded the episode on his own. The voices and animation style are still the same (which is almost sorta a bummer - would have been pretty neat to see Adventure Time made entirely as an anime), so it won't be TOO much of a departure.
Here's the clip that was released at WonderCon - the episode's called "Food Chain" and it looks like Finn and Jake are about to learn a lesson in caterpillar-cuisine.