So, there are some structures at Venice beach where spray painters (graffiti artists) are legally allowed to do their thing. There was a long time in which no permit was required, then that changed. So, they put up a sign saying that you need a permit to paint on the provided walls.
Thing is, the sign itself would naturally be a target for graffiti and it wouldn't take long for taggers to completely cover up the message. So, the friendly folks at Venice Beach did something really smart. The words on the sign pictured above are actually cut-outs. It is impossible to paint over this message. Although that didn't stop someone from painting the sign the same color as the surrounding sand rendering it almost invisible.
For more, see: VeniceArtWalls.com