i)The phrase "fair igloo" is an alternative way of saying the more common and respected phrase "fair enough". It can be used in a way to emphasise the fact that you are being ironic, showing that you do not think it is "fair enough".
ii)Though it can also be used to express the opposite of being "as hard as nails" to show weediness, pussyish behaviour and all round weakness.
i) Bob : "Fecking furfag; go and eat some fur!"
Carl: "Ah so that is what you think of me is it? Fair igloo, there is some nice fur waiting to be nibbled on just outside my door!"
ii) Bob: "For cocks sake Carl, your about as tough as fair igloo!"