It is a triumph of grown-up cut-and-paste. Whoever was responsible for customising a harmless Wicked theatre poster had taken quite a lot of trouble to print out the word Wankers in special 'Wicked' font; find the right pictures of Gordon Brown and Alistair Darling, with heads tilted the appropriate way; tint Brown's face green; make everything just the right size to match the original. I was so impressed I have had to break out the semi-colons, which is unusual indeed.
I genuinely have no idea if this spoof is an old gag, if everyone else has already seen it on some kind of viral email. Have they? But even if this is the case, the perpetrators had still taken the time to craft it, and wile away their journey from East Croydon to London Bridge or similar cutting bits of paper out and brazenly making use of a Pritt Stick.
In my bovine morning state, it took me a while to notice it wasn't actually the real poster. The clue that gave it away was that – ha! - Alistair Darling is coming unstuck.