Irritating

I don't know why, or who, but someone is irritating me in a big way. I've started noticing when I come out to my car in the morning that someone has written on it. Most often I can't read exactly what it says (the person in question has poor writing), but there have been a few 'messages' that I can see properly. Everything from F-bombs on the roof of my car, to something with the word 'suck' on my hood. I had 'F*** Yah' (apparently there was confusion over how to spell "yeah") on the driver's side rear window, and and a reference to male genitalia on my front driver's side window. Most often it's just written in the frost that builds up on my car, but the past two words/phrases were written in road dust. It doesn't really bother me, except that I have to do a walk-around of my car each morning to make sure I don't drive off with something really offensive scrawled on the side.
I'm really not sure what bothers me more; that they're writing on my car every morning, or that they're not writing anything of value and are spelling things wrong. Please, go ahead and scrawl on my car, but make it something interesting! "Balls" just doesn't cut it.