Cuppycake.com (a site that predates ytmnd's remix, as does e-thug) has more on the history of the recording and the child who performed it: Link. What's that? You want to know the lyrics? Got some Cuppycake Comments you're dying to get off your chest? It's also available as a wingtone for your tewephone. (Thanks, Bridget and Mike D, and Mike Atlas !)
Reader comment: Cody "codeman38" Boisclair says,
Wikipedia, as usual, has the scoop on the origins of the cat-loaf-- or 'Nekopan', as it's known in the original Japanese: Link. It's a character created by illustrator Hirose Takuro, whose home page can be found here. Sadly, there's not a whole lot on either the character or the illustrator on the English-language web; I could no doubt find a lot more relevant info if I knew more than just a few words of Japanese...
Update: Here's another animation take on Cuppycake: Link (Thanks AC)