This is the best description of my mind racing at night I've ever found:

Back on the couch, he counts. One little sheep, two little sheep, three little sheep. Why not? The sheep trot up the fences - he's got their fat-assed waddle down cold - but he can't make 'em jump. Do sheep jump? They're unaerodynamic, their legs are too short. And so after imagining a few sort of levitating over the fence- their little legs dangle, wobbling back and forth in a light prairie breeze - he gives up and lets them walk along it. the way real sheep might, and munch on the grass that rings the posts. It's a split-rail fence: he knows real sheep would be penned behind a wire fence, or perhaps an electrified fence, but how relaxing are realistically restrained livestock? The split-rail fence is idyllic, rough-hewn, it allows him to imagine the sheep scratching themselves against the coarse-grained wood. But wait: they're scratching a bit too hard, aren't they? In fact, some of them have got these bald patches, and their skin in pink and inflamed...oh, no! These sheep have scrapie, the ovine mad cow disease - they're doomed! And sure enough, as he comes to this grim realization, the scrapie-afflicted sheep begin to collapse, until they have formed a large fluffy pink-and-white pile at the edge of the meadow.

~Mailman, J. Robert Lennon