This question already has an answer here:
Some people act in ways that provoke surprised or shocked reactions from others, mainly because they enjoy getting those reactions and not because of any inherent desire to perform the action itself. For example, I suspect that this is a primary motivating factor behind the recent Brony phenomenon -- the My Little Pony show itself would probably not attract hords of adult male fans, were it not for the incredulous reactions which the fandom elicits. Is there a word to describe this sort of behavior?
("Provocative" seems off -- it refers to the fact that a reaction is elicited, but not that this is the motivation behind the behavior.)