Okay a question for the English here; what the hell is this "Bedroom Tax" everyone is going on about?

People living in social housing (council housing) will have a financial allowance reduced if they have spare bedrooms. Not strictly a 'tax' but called a tax by the media. The idea is to free up social housing with several bedrooms (for large families) by getting people to move to smaller houses when children have moved out as they grow up and want to be independent. Naturally this will produce disruption or financial strain to those involved.

Wikipedia is your friend!

"Among the provisions of the [Welfare Reform Act 2012] are changes to housing benefit which came into force on 1 April 2013. These changes include an "under-occupancy penalty" which reduces the amount of benefit paid to claimants if they are deemed to have too much living space in the property they are renting. Although this penalty is not technically a form of taxation, it has been characterised by the media and political commentators as the "Bedroom Tax", linking it with the public debate about the "Poll Tax" in the 1990s."