Chalk

Someone, or group of someones, had a very busy night last night. We woke to find the whole street and sidewalks covered in chalk drawings and statements, colorful, lots of pictures of bicycles. Most of it has now disappeared, smudged from being driven and walked over. This is the only phrase that is still readable.

Edit. Here's a transcript of what it says:

Your pedigree doesn't stand next to mine I'm a thoroughbred a most excellent kind