Which way does she spin? Clockwise or counter-clockwise?
No, it's not a trick question. You'll see her spinning one way or the other and you won't be able to figure out how the HELL anyone can think she spins the other way.
Unless, of course, you see her change direction. I have looked at the actual animation frame-by-frame, and that doesn't give any "after a certain time, she spins the other way". No. Frame-by-frame, she spins clockwise. First time I looked at it, she was going counter-clockwise and I was thinking there's no way you could see her as spinning clockwise. Then, all of a sudden, she did. And when pointing this out over MSN, it changed again! And as I was writing it again, it changed mid-sentence!
I remember a few years ago, doing a test about which half of the brain you most use, I was quite close to the middle, with only a few % more to the left side. Maybe that's why. Either way you look at it, prepare to feel mindfucked!