Beijing police have problem with … “Sarks”?

If you live in southeast Beijing and spend all your time staring at graffiti like I do, you may be wondering who the “Sarks” are. They seem to have claimed a wide area including playgrounds, video arcades and hotels.

Is this one a coincidence or spelling error?

“Sarks” sightings:

I’m still waiting to meet Frank.

Frank’s in the backyard of the game arcade, thinking about peace and love.