Well... our brains already flip what our eyes see horizontally, so I'm sure it can do the same vertically.
whargolflorp
that would probably hurt, and eventually your roof would cave in under the weight
dynizard
actually your eyes would eventually flip themselves back over, but inverted, so either way you'd end up with a horizontal flip.
MikeJHoyle
They already flip it vertically, actually, and it's been demonstrated that one's brain will start to see 'the right way up' after a while if one wears glasses that flip what you see