User blog comment:PurplePenguin/The Grunkle Stan Mystery/@comment-96.246.243.132-20120729025433/@comment-67.54.173.224-20121021003614

I've been thinking about the thing messages in the theme song as well. I all caps what I find suspicous:

"Stan is not WHAT he seems"-instead of not WHO he seems. Now, this could mean nothing, and it could mean everything. I personally don't know about the immortal thing, since I've always thought being immortal as completely insane, personally, again, really, but I heard on another gossip site that he could be a werewolf, going into the room after the last light goes out so no one can see him as a wolf.

Then "I'm STILL here". I've read a lot-a LOT-of theories about this, from the author still being alive and, by extension, telling us about Stan, to it being Jeff the gnome because he's in the first episode and is coming back.