The holiest of days in many a marijuana users’ calendar is upon us: The 20th day of April, the hallowed 4/20. There’s much on in the Bay Area today to mark “the stoners’ Christmas,” as the day has been dubbed.

But there’s also much more going on than the annual smoke-outs at 20 minutes past four in the afternoon at Hippie Hill in Golden Gate Park, the University of California Santa Cruz campus, and essentially anywhere else marijuana users are known to congregate (read: anywhere). The time — 4:20 p.m. — is important. In the 1970s, a small group of hippie stoners at San Rafael High School would go out every day at that time to smot pot, and their “club” name just stuck.

Today, activists are asked to turn out for a protest in Oakland at the downtown Federal Building at 11:30 a.m. Participants should congregate at 1301 Clay Street, where the California chapter of NORML — the National Organization for the Reform of Marijuana Laws — will agitate and educate in response to the Justice Department’s crackdown on state-legal medical marijuana dispensaries…