I guess it's art, appears to be plastering USPS stickers with messages all over public property. Covering the All-Way kind of sucks though, some tourist might not catch that one (recently driving in San Fran I have to say there were a few all-ways that I'd sit at for an extra long time not realizing they were all ways, and expecting traffic to keep moving on the other streets).
My favorite street-art falls under vinyl stick-em graphics like the following.
I think even with an awkward looking character, and a message to follow it you might draw more attention then "Asshole" from people who stop to read it. Maybe an "aww, that's cute, nice saying too".