4:20 is code for the time of day stoners allow themselves to blaze. The genesis of this custom is hazy (of course), though High Times magazine once pegged it to a group of high school students from San Rafael in 1971 who appointed said time to search for a stash. April 20 evolved into an international viper holiday, and what better way to spend it than sitting in a dark movie theater with other baked heads while watching an uber-trippy concert flick? 1977's The Grateful Dead Movie was shot three years earlier in San Francisco at the end of the mighty band's first golden era. It's a glorious time capsule of a freer America when one could be publicly psychedelicized without a SWAT team arresting you for jaywalking. (At least not in Frisco.) Co-directed by lead guitarist Jerry Garcia, the film contains thrilling live footage of the Dead at their height and fascinating interviews with early Deadheads as well as sundry set-pieces such as wrecked roadies sucking on nitrous and bassist Phil Lesh hilariously playing with feedback during set-up. The opening animated sequence of the iconic Uncle Sam skeleton riding a Harley is a classic. The film will be shown at 540 theaters around the country tonight with a never-seen Garcia yap session. Wednesday, April 20, 7:30 p.m.; for theater location and prices, go to fathomevents.com.

Wed., April 20, 7:30 p.m., 2011

Advertising disclosure: We may receive compensation for some of the links in our stories. Thank you for supporting LA Weekly and our advertisers.