Graeme chains David Platt to a radiator - but why?

This has got to be one of the funniest Coronation Street pictures I've seen in a long time. It's David Platt chained to a radiator, of course, and why not? It happens when Graeme decides to tell David that he's now dating Tina and in order to be sure that David's not going to punch his lights out, Graeme chains David to the radiator in Gail's house first before delivering the news to the Plattser. By the look of things in the pic, David yanks the radiator off the wall and goes in search of Graeme...