When I was a kid, some guy in my town had a ratty ass van, a real POS, and on the side was spraypainted, "Don't laugh, your daughter might be in here"... Years later, A friend of mine had a van in his yard that his dad stored parts in, on the side they painted "KEEP OUT OR DIE!" I gotta say, they lived in a fairly rough neighborhood, and nobody ever stole anything from them... It was a landmark of sorts, when giving directions, the van was always a visual aid...