The Situationniste Internationale (Situationist International) was a leftist politcal and artistic group based in France. Best known for members Raoul Vaneigem (the author of The Revolution of Everyday Life, a direct predecessor to TAZ, as near as I can tell) and Guy Debord (author of Society of the Spectacle), the S.I. was responsible for some prescient and brilliant critiques of modern Western society.
Their name arises from a few terms defined in the first issue of Internationale Situationniste:
A deliberately constructed moment of life, based on environment and events? While the phrase "free play" may be a happy coincidence, the idea seems--if only in its insistance on the temporary nature of the situation--to be a precursor to some of Bey's. So, too, does S.I.'s deliberate attempt to defang academic interpretation; Bey's tongs and Immediatism are colored by their refusal to play along with the all-seeing eye of the mediated society.