First, let me say this. I'm not a proponent of vandalism. You should always respect things. But there are those instances that warrant creative expression. And one of those ways is by voicing your opinion as a display of a mild form of vandalism.
It could be to oppose something or even spread some cheer. Whatever the case might be, these are some examples I approve of, so check them out and judge for yourself. Something tells me that you might enjoy it more than you think.