This is a video of a dual axis optical illusion of a rotating Lissajous curve (frequency relation 2:3) transformed into 3D space that appears to rotate around a vertical axis when viewed regularly or when moving your head from side to side, but appears to rotate around a horizontal axis if you move your head up and down. *shrug* I don't know, I have a headache now.
Keep going for the video, which might work better than the gif.
Thanks to Bernd, who agrees the best illusion of all time is the detachable thumb trick.
These are a couple video demonstrations of the jellyfish animation drill-powered flipbook created by Instagram user wolfcatworkshop. Apparently the flipbook will eventually be handcrank powered, he just...