There is a graffiti artist in Spain and his tag, his nickname, is, "Dr. Hofmann". You see it written everywhere, even in out of the way places. Especially on the island of Ibiza (e-be-suh'), even on back country roads on Formentera, the next island over.
Spanish street art is great! I have a folder full of images from Barcelona of nothing but that... must find it and share some here