A quicker way of saying "Japanese Animation", which could furthermore be generalized has simply "Anime", which is less fun to say than Japanamation.
"Let's watch some Japanamation!"
any cartoon that is Japanese and then translated into English. Some examples are Dragon Ball Z, Voltron, or Astro boy. Usually the story revolves around fighting, and the animation is limited. There is both good and bad Japan-a-mation, for instance: FLCL-good(good animation, with original story with a lot of underlying subtext for both a older teen and adult audience). Yu-gi-oh - BAD(why do you want to watch other people play a card game, and the plot seems as if the writer just makes the crap up as he goes).
Oh snap, Goku just ripped that guys eyes out from the back of his head. That's some good japan-a-mation.