As you'll no doubt remember, the Irish government recently found an extra 3.6bn euro it didn't know it had. Bizarre, right? Well, it turns out there's a good bit of this about!
Last week, Germany found a little windfall in a nationalised mortgage bank; 55 billion. And the week before, the US government found 6.6bn dollars it thought it had lost in Iraq.
Perhaps the entire financial crisis was caused by national governments losing a billion here, a billion there, down the back of the couch.