A very rare first printing of the sought after poster "Trip Or Freak" advertising a San Francisco concert on Halloween, 1967 featuring the Grateful Dead, Quicksilver Messenger Service and Big Brother & The Holding Company (featuring Janis Joplin.) This legendary poster is a collaboration between Stanley Mouse, Alton Kelley and Rick Griffin. There's a legend that many of these were cut up for the hundreds of small skulls making up the background–which were impregnated with LSD and sold as blotter acid It looks near mint now, with some very light creases on top and bottom. Corners are perfect and never mounted. A beautiful example of a rare and highly collectible poster from the classic era of San Francisco rock. Measurements are roughly 26 1/4” x 14 1/4”.