BACK IN THE heady, innocent days of the early '90s, someone coined a colorful term, "alternative rock." For a little while it actually meant something. A cadre of bands defined the genre by what they weren't as much as by what they were, flouting mainstream classification and radio-friendly pop simplicity to instead cater to a small niche of fans who sought daring, defiance, and intelligence in their music.

On the fringe of the fringe was Primus. Math rock for metalheads, funk for punks, all dark noise and cartoon imagery, Primus's music reveled in odd juxtapositions that spoke to the conflicted, semicynical heart of the alternative anticlique. Les Claypool played rotund, skull-rattling bass like a pied piper. He took the instrument from its overshadowed rhythmic role and refashioned it in a bombastic, totally original lead style. Larry LaLonde's crunchy, angular guitar was the steely yin to Claypool's throbbing yang, and Tim "Herb" Alexander's lyrical, firecracker drumming put the whole insane wheel in motion. After Primus spent a couple years mangling loyal Bay Area fans, MTV and Interscope caught wind. Claypool was labeled a genius, and for a time Primus enjoyed both mass popularity and underground approval.

Unfortunately – and inevitably – they bought into their own media hype, skewing too overtly silly to remain relevant. In '96, LaLonde and Alexander left the band to pursue their own projects, and Claypool carried the torch for four more years until he dissolved Primus to devote attention to his myriad supergroups.

That's where our story picks up. The Warfield Oct. 30 felt extremely 1996. Maybe it was the ponytails and trench coats, the faded black concert T-shirts, or the giddy, high school pep-rally thrill buzzing through the crowd, but there was a distinct throwback vibe in the room, and it felt good to be among the former geeks, stoners, and misfits who knew a good thing way back when and were excited to revisit the soundtrack of their formative years.

This stop on the Tour de Fromage, which brought the original trio back to San Francisco for the first time in more than five years, was slated to feature songs from the early Primus catalog for the first set, then a start-to-finish performance of Sailing the Seas of Cheese (Interscope), the band's 1991 breakthrough album, for the second. By show time the thoroughly drunken crowd was chanting, "Primus sucks!" as Colonel Claypool and company hit the stage with a manic smash-up of "John the Fisherman." Fists pumped, heads banged, and the band looked on with bemused detachment, somewhere between dreamy reminiscence and ironic presence. No doubt Claypool has a Floydian complex: next came a powerful, eerily to-a-T rendition of "In the Flesh" from The Wall. "So you / Thought you / Might like / To go to the show ..." he crooned through his nose, and at that point, the crowd knew exactly what it was getting into. A couple songs from later albums followed, "Southbound Pachyderm" and the brand-new "Pilcher's Squad," which were stretched out with elastic interplay between Alexander's double bass drums and Claypool's rubbery bass. There Claypool's recently acquired penchant for jam-band meandering was evident, but the groove remained focused, solid, and heavy. He rode his fretless over the stage like a thin-necked pony; Alexander flew across his immense percussion array with flawless intensity. The set ended with two faves from Frizzle Fry (Caroline/Prawn Song, 1990): "The Toys Go Winding Down" and "Mr. Knowitall," which had all the maniacal menace of a psychedelic carnival.

Clearly the crowd had saved its strength for the Seas of Cheese set. At the first notes of "Here Come the Bastards," a mosh pit erupted in the orchestra, with limbs and hair flying. "Jerry Was a Race Car Driver," "Is It Luck?," and "Tommy the Cat" all showed that the band was in prime form and clearly out to awe rather than merely go through the motions a typical reunion show might inspire. Claypool alternated between his four- and six-string basses and, for "Fish On," brought out a weird whammy-bar upright, tweaking long, loping notes before igniting the frenzied instrumental breakdown. For the finale, "Los Bastardos," several costumed freaks – including George W. himself on guitar – came in for added oomph, inspiring the most ferocious blowout of the night. After a locomotive "Harold of the Rocks" encore, Claypool reached into the air, shook his hand, and walked away.