Even if you've never seen an episode of SpongeBob, you've gotta admit this is pretty funny. (For those who haven't seen an episode, Gary is SpongeBob's pet snail. All snails sound and act like cats where SpongeBob lives.)
Apparently the voice talents behind SpongeBob and his friends wanted to prove they were capable of more than just cartoons (or so goes the story they tell anyway). Heh heh. The "Singin' in the Rain" bit still makes me laugh.