not sure whether this is a repost or not, but here it goes:
go to your profile page and press: up, up, down, down, left, right, left, right, B, A, Enter. You should be getting a lens flare mode whenever your mouse does an action
from http://thetracebook.blogspot.com/2010/02/konami-code.html
more facebook stuff on http://thetracebook.blogspot.com