depends on how much it pisses you off IMO - if it was me i'd start polite - then go from there

this happened to someone who parks cars in this street i pass on my way to work - driving to work one day and the 3 cars he had for sale down there had paint brushed on them.

now i'm not condoning this, but i did piss myself laughing - funnily enough i never saw a car for sale in that street again