Can anyone else shake their eyes?!

Can anyone else shake their eyes?

For as long as I can remember, I have been able to shake my eyes. It looks, from other people's perspectives, like my eyes are vibrating from side to side. From my view, it looks lke I'm in an earthquake. I can do this whenever I feel like it, and it also tends to happen when I'm really concentrating on something, and/or if I'm tired. Anyone heard of this before, or know what it is?

2 weeks ago
No, my eyes never ache from doing it, but yes, I start to get a headache after about 10 seconds or so.

I don't know how I discovered I could do it! I think I came to realise that it wasn't something everyone can do when I was about 8..

Cool!!!!!!!!!!