Yes, I suspect it's about pizzas. I'm quite perceptive sometimes.
Seriously though, those fellas in England that sneak into a farmers wheat fields and make strange patterns in the night must make the farmers absolutely furious, when he finds a good part of his crop ruined. Anyway what sort of aliens would fly around thinking "oh man, I've just got to leave a sign on this planet before I go, I must find a wheat field, about a month away from harvest, if I can't find one, I'm sunk!"