Any idea's what fancy dress to wear to a freeze party?

I'd do eskimo. That will keep you warm and stay in theme. Or polar bear! For eskimo you just need a thick jacket with wool inside and a hood. The polar bear you could make some pants and shirt out of a white or cream coloured felt or velvet type material. You could go as bobby from x-men... but that is a bit hard to do. What about a penquin... in a little suit! That would be great...