An individual who defecates on a public sidewalk in front of a group of unsuspecting passers by. This individual generally lurks around corners and waits for large groups of tourists before making the sidewalk his canvas.
Ramon: Oh my god, is that guy's entire ass out?
Scott: Let's cross the street. That guy looks like he is a textbook sidewalk painter.
Bill was tired of the noise outside his house, so he hired a sidewalk painter.