Happenings can be a form of participatory new media art, emphasizing an interaction between the performer and the audience. In his "Water", Robert Whitman had the performers drench each other with coloured water. "One girl squirmed between wet inner tubes, ultimately struggling through a large silver vulva." Claes Oldenburg, best known for his innovative sculptures, used a vacant house, his own store, and the parking lot of the American Institute of Aeronautics and Astronautics in Los Angeles for "Injun", "World's Fair II" and "AUT OBO DYS". The idea was to break down the fourth wall between performer and spectator; with the involvement of the spectator as performer, objective criticism is transformed into subjective support. For some happenings, everyone present is included in the making of the art and even the form of the art depends on audience engagement, for they are a key factor in where the performers' spontaneity leads.