It's his evil grin. ._.
By the way, the reason why it looks so scribbly is the fact that it only took me about five minutes.

Oh, and for all of you who don't know, FuzzButt = Allamorph.

Here is the better quality picture: http://fc04.deviantart.com/fs46/f/2009/233/5/9/FuzzButt_by_Driffter.png
JPEG wrecked it. Dx