Wiggle Aquatic Cat Worm gif
Adam Rifkin stashed this in Lolcats!
From Reddit: "I used to think it was a kitten thing, a warning to it's siblings prior to a play hunt and pounce. Turns out it's for normal balance, however it definitely happens a lot more regularly in young cats. Seems a bit odd to me because that movement is likely to scare off any real prey."
Maybe it mesmerizes its prey, like when a cuttle fish strobes.
Makes sense. I'm mesmerized by all the cats above, and that includes Shaq.
I am still mesmerized.