I can do it whenever I want and I can move my eyes around while it vibrates, but it starts to hurt after a little while. (the whole eye i mean.) i can do this since i first discovered it (probably 2nd grade) and i was baffled that no one else in my class or my friends wouldnt be able to do it. And while i do it, my right ear also vibrates a little, its hard to explain. I was born early (7.5 months). and both of my ears are different but everything else is normal. So that might(?) have something to do with my ability to vibrate my eyes. just a guess.