Caption This Photo: Sidewalk Economic Indicator

As you can plainly see from this photo (click for full size) taken on a San Francisco residential neighborhood sidewalk, we could never make this up. We could also never properly describe this Sidewalk Economic Indicator. Who left a mess of clues like this? Was it a Realtor or mortgage broker who turned to drugs? Or was it a pre-Med student who then chose real estate just before the market crashed? Please caption and/or quip with your theory.