I think it's short for weasel - a nasty, sneaky way of getting out of your legal and moral obligations. Something Boko professes to be an expert at.

I don't think I'm an expert at anything.

As a result of the mess left by brown's government, HMRC simply do not have the manpower to collect tax due from companies that have been dissolved by Companies House - to quote the tax officer "it's regrettable, but that the way it is."