Um, I think it's just some harmless fun. Not clever though.
Recently, I've seen some really clever graffiti on those "Stop for me it's the law" signs, that have pedestrians in a walking pose. It gets changed to "Stop for me it's the Claw", and they draw a little claw on the pedestrian's hand. At least that's clever.
Here we go:
http://www.larryswanson.com/wp/2008/...-its-the-claw/