I recently bought a set of Smartballs, and had just put them in. I was swaying from side to side getting them to move, then stood up and giggled at how the felt. My boyfriend, highly amused by the whole thing, promptly picked me up and shook me up and down. I almost died from the feeling!
(Side note: The Smartballs are glorious on their own, without added shaking.)
(Side note: The Smartballs are glorious on their own, without added shaking.)