These have been popping up recently in my part of the world. Mostly on freshly dig and filled holes in the road or footpath.
Initially they looked like a political message, seeing them in Newtown. Do they mean West Papua New Guinea?
But since the stencils keep appearing on tar filled holes, maybe it is an acronym for the company doing it: Weird Pipes N Gaps
Searching for ‘wpng’ have not been very useful, mostly brings up results about a Portable Network Graphic program. Though I did get one for an Oregon natural gas company.
Have you seen these and have a better explanation?