It's saying: here I am, my eyes are open, so I'm at least pretending to listen. I'm kinda smiling, but not enough to see in a 100x100 picture. If I weren't smiling, I'd look mean, and I don't want to look mean. But if I were smiling a lot, it'd be inappropriate for so many posts, and I'd look like a goof. So this is the middle ground ... mild, indiscernible smile.
It's also saying: screw you, I'm only half-smiling because I made this 100x100 JPEG with 100% quality, using 1x1 sub-sampling and floating point, so it takes up a ton of bandwidth and CPU for you to download and decode. Hah! If those 40k animated GIF people can make you download 40k of crap, I can make you download 10k of pretty me.
Yup, that's what it's saying.
And it's asking: "What's that flash doing all that funky shit for?" Ah, but you'll note the lack of red eyes, my friends.