The smoke machines were on at the Cypress Hill 4/20 show last night — and by smoke machines we mean the blunted fans who showed up en masse at The Warfield.

I didn’t take long to figure out what kind of night it would be at the group’s sold-out sixth annual 4/20 celebration. In the outer corridor of the venue, just after the entry, a girl sat dazed after passing out from a few too many celebratory spliffs. At least five more (that I saw) would join her as the night continued.

Inside, closer to the stage, was pure reefer madness as the Literates warmed up the crowd in an already thick cloud of smoke. Far too often at hip hop shows the opening act is sub par, but the L.A.-based trio held it down and had the crowd enthusiastically jumping and waving its arms — a difficult job with this heavily sedated bunch.

For the main event, Cypress Hill brought the energy to another level, emerging from backstage with leather Cypress Hill motorcycle gang jackets. A bit ironic, considering there was some real motorcycle gang drama when a fight broke out in front of the venue during Lauryn Hill’s show last week.

Weighing heavily on classics from its first album early in the set, Cypress Hill kept it live with “How I Could Just Kill a Man,” “Hand on the Pump,” and “Real Estate,” peppered with simulated gunshots and shotgun blasts.

The group let its Latino roots shine with Sen Dog taking front and center and B Real joining Bobo, the group’s long-time percussionist, in the back. But the crowd was waiting for the third act — B Real, joint in hand, running through a medley of Cypress Hill’s stoner anthems “I Want to Get High,” “Hits From the Bong,” and “Stoned is the Way of the Walk.”

A few more classics from Black Sunday and Temple of Boom, and a brief interlude into Cypress Hill’s ill-advised rap-rock material, and the show was at a close. The crowd, still basking in a smokey haze, seemed satisfied.