Went to get in my car for work this morning only to find this little gem written on my car with permanent marker, bit disappointed they didn't have the balls to stay around and colour in the arrow properly, suppose I should be impressed they managed to spell it right though eh?
Spray any kind of deoderant (not anti-perspirant) and wipe with a soft cloth and it will come right off with a little elbow grease. Even better, if you've got some isopropyl alcohol sitting about, it will wipe off like it was just dust.