Goings On in the 50s and 60s:

They were non-verbal, theatrical productions that abandoned the stage-audience structure, did away with the usual plot or narrative line of traditional theatre; made objects of the performers and set them within an overall design of environment, timing, sound, color and light. They were accidental, spontaneous and planned — each a unique event shaped by the action of the audience that participated in it.

See: “Happenings in the New York Scene (1961)” (Kaprow, Allan, Essays on the Blurring of Art and Life, University of California Press, 2003) ” ?a happening cannot be reproduced. The few performances given of each work differ considerably…and the work is over before habits begin to set in.?