In a bus tunnel in São Paulo, Orion is doing a large scale portrayal of skulls, almost covering a wall.
At first it looks graffiti, but the skulls are symbols chosen carefully. You see, Orion crates the images by cleaning away the soot and pollution that have been accumulating on the walls. And, by extension, in patrons' lungs.
The authorities thought at first they could bust, or at least stop, Orion using vandalism charges. But the images aren't permanent, and there's nothing illegal about selectively cleaning property. So they cleaned off the part of the wall Orion had "drawn" upon, thereby removing the images of the skulls.
Whereupon Orion did the same treatment to the remaining uncleaned parts of the tunnel.
The authorities have now gone and cleaned all bus tunnels in São Paulo, just to cut Orion off.
That will probably not be the end of the story. Orion's guess is enough soot will be back to make new images in about three or four months time. If so, he'll be off to the races again.
akirlu's reaction when I told her this: "That's a sweet piece of manipulation."
(I forget the exact source for this story, but I seem to recall it originally being mentioned in some photography or sculpture forum somewhere. It's because the comparison is to art where one takes things away.)
((UPDATED TO ADD: holyoutlaw reminded me just right -- I first saw jeliza point to this link. When I was searching through my FL for the entry, I was using the wrong search term ("sao"). Damn geographic memory.))