Early in 1991, someone was walking through London with two friends, from Camden Town back down towards the centre of the city. They stopped to wait at a pedestrian crossing for the lights to change (the standard British plain red silhouette of a man standing upright, if you're not sure). It was the corner with the restaurant Ruby In The Dust on it.
As usual when waiting for the lights to change, they all watched them impatiently. Eventually they switched over to the British green man (a walking silhouette shown mid-stride) and we started crossing. As they walked, they kept an eye on the lights to make sure they had time to make it across comfortably. Some of those crossings in London are a bit rough. About half way across the road, there was -- quite literally -- a ripple in reality, a brief flash of disturbance, and suddenly the lights had changed again... but not back to red. The plain green guy was now wearing wide-bottomed flares and glasses, had long, flowing hair cascading out behind him, and had a line of stars from in front of his forehead that trailed over his head and down his back, each one slightly bigger than the previous, like some kind of cloak. They all stopped dead and exchanged stunned looks. Then they remembered the traffic and hurried across the road, and waited nervously for the lights to go red again. Sure enough, on both sides of the road, the red guy had changed too. He was now carrying a briefcase, smoking a pipe (with wisps of smoke rising), wearing a little homburg hat, and he had big brogues on his feet. They watched at the lights cycle for ten minutes or so, but eventually continued on, feeling really freaked. The only explanation that can even begin to stand up to Occam is that they briefly swapped into a closely-aligned parallel dimension. Something that, well, pointless... could happen all the time really, and 99% of the time you'd never notice. It's a strange old universe.