There’s a Matt Groening cartoon called “Kids Want To Know”, reproduced by Greil Marcus in Dead Elvis, in which one of the “Life In Hell” rabbits is glumly musing upon various difficult questions. “Which would you rather do,” he asks himself, “slide naked down a 50ft razor blade or suck the snot from a dog’s nose until its head caves in?”Fairly primal fears, these, and the choice between excruciation and disgust is tricky. But no-one’s going to suck dog snot by mistake: it will never be much of a surprise. But imagine a razorblade was placed maliciously on a waterslide, and a sequence of events which might run like this:

swimming fun -> desire for greater excitement -> whooshing happily down the waterslide -> sliced lengthwise by a razorblade -> not feeling it initially -> slow but quickening sting of chlorine as you plunge into the water -> tell-tale spread of blood in the pool -> realising the blood’s yours.

It’s not just the pain, though razorblades on the waterslide are likely to be painful at best. It’s the randomness, and the helplessness, and the miserable shock in the juxtaposition between innocent fun and potentially grievous injury. Most fearful of all is the delayed realisation, arriving in the form of the sharpest of stings, and only when the damage has been done.