I love April Fool billboards, they seem to inspire the fiendish iconoclast wordsmiths who produce them to new heights. Today's was the perfect exemplar of what I can only think of as the April Fool Hesitation, the momentary buy-in which mines the Pavlovian response via which we instantly and instinctively accept as real any major event which a newspaper describes. The true enjoyment of the joke is in the clash between that second of belief and the immediate realisation of its falsity - your mind falling over itself for long enough to create the classic delayed drop.
The perfect construction of this headline to me hinges on "SHOCK", because it frames the "fact" - Cape Town bidding for the Winter Olympics - as outlandish in itself: that is, it mimics perfectly the stock media response to something extreme and unlikely, rather than attempting to naturalise the bid as reasonable. (It also plays subliminally on our awareness that SA's World Cup hosting and various Olympic bids in fact make no damned sense anyway). That incredulous distancing is nicely judged to elicit complicity, to pull us into the illusion of belief for that vital second before the realisation, and the comic conflict, hits. The effect was to cause me to drive for three blocks in a fit of the giggles.
I could go off on a tangent about the subtextual environmental commentary in the idea of snow in Cape Town, but it's the kind of reading which would require me to expend green ink writing "this is a bit stretched" in the margin of a student essay, so I won't.