Clicking this image you can watch a very disturbing site with photos and information about the use of skeletons for black humour in the early 20th century photos, drawings and other stuff. Even today, some people feels scandalized by recent exhibits - theatre plays, happenings or whatever - in which the authors try to provoke new emotions and explore until now hidden areas of the human soul. I don't have the need to be disturbed by that kind of thinks actually, but what makes me laugh is the pretentiousness of some self called artists who like to cross some lines -a s if they were pioneers who discover an unexplored new world - when, in fact, all that is so so old!
I guess that a real provocation was what they did the Romans, feeding beasts with Christians for recreating old mythological legends. Some of those spectacles were sold with the incredibly hypocrite publicity that they were 'highly educative for everybody, even the children'. In my opinion, all this - as it was in those old days - is bullshit.
I ever liked (I think I mentioned this quote more than one time here :D) what said Luis Buñuel about it, when he was old. When he was younger he was involved with the Surrealist group and he became famous for shooting Un Chien Andalou and L'Age d'Or, both very provocative and anti-clerical movies. Later, he found all those attitudes very childish and he ever felt pissed when some artist wanted "to provoke" self-consciously, saying: "After Hiroshima, Nagasaki and the Jew Holocaust any artist who pretends to provoke the society - épater le bourgeois - is an ingenuous or an imbecile."