It's about time you had another look at those <a href="http://www.theregister.co.uk/2005/07/13/the_return_of_the_irony_tag/">humour tags</a> Andrew: a number of your readers seem as impervious to hyperbole as they are to sarcasm, irony and other such (ahem) advanced manifestations of the written word.
Although, that said, you'd have to give that one a new tag all of its own as there was no category I could see that specifically covered "exaggeration for humourous effect" and you wouldn't want people misled into laughing at the wrong type of joke, would you?