Here's [yet] another of my airshow photos in which I blatantly ignore the actual planes.
This time round I was more interested in the arrows and labels I kept seeing on the sides of quite a few planes. Labels like these:
Someone wiser, more aeronautically knowledgeable and less facetious than I would probably tell you that it's something related to static electricity and avoiding sparks when re-fuelling ...
As for what I'd tell you ...
... well, I'd tell you that it's a notice all planes have to have in case the pilot forgets where to land.
Believe what you will.