A distracted man with a personal stereo and a big grin on his face wanders off the end of the down escalator and turns towards the southbound platform. Once on the platform, big grin still plastered across the front of his head, he paces around the platform impatiently waiting for a train to arrive.
Up he paces, then down again. Up and down in an aimless yet amiable manner he wanders. He turns round to peer at the "next train" display, takes a few more paces and suddenly realises he's run out of platform.
Just managing to keep himself upright he staggers backwards, narrowly avoiding planting himself head-first across the live rails. He looks perturbed for a few seconds before pulling himself together and resuming grinning and pacing, only this time paying just a little more attention to where he's going.