I'm guessing Altamont - notorious end to the peace and love generation - the Rolling Stones did a gig at Altamont race track and 'hired' the Hells Angels as security - they killed a fan (with or without justification depending on whose report you believe) http://en.wikipedia.org/wiki/Altamont_Free_Concert I don't know why but that's what I immediately thought of when I saw the picture - although I've never heard pool cues were involved.
