A Jazz Fest nighttime staple is the once-in-a-lifetime (or at least once a fest) aggregation of musicians who rarely play together. The crew tonight at the 12 Bar on Fulton Street is one of the more unusual such groups, involving members of Down, Dash Rip Rock, Cowboy Mouth, Supagroup, Morning 40 Federation and Egg Yolk Jubilee, and they’re uniting behind punk singer/provocateur Jello Biafra for a night of New Orleans R&B covers.

“I’m doing it on a dare,” Biafra says. He saw a recent Cowboy Mouth/Dash Rip Rock show in Colorado, and when someone backstage heard him singing along to the covers portion of recent Cowboy Mouth shows, he was told he had the voice for the songs.

“I guess I do,” Biafra answered. “I guess we’ll find out, won’t we?”

The idea’s not as unusual as it might sound. Though little in Biafra’s recorded career suggests an affinity for New Orleans music, he points out, “My musical roots are very, very wide and very, very deep. I practice my craft by listening to thousands of songs and figuring out what makes them work.”

Like so many music fans of a certain age, the Beatles were his starting point – in his case when he was only 7. “I quickly gravitated to the harder stuff,” he says. “Early Stones, Paul Revere and the Raiders, Music Machine, Denver bands that got played on the radio then like the Moonrakers and the Astronauts.” He moved to the MC5 and the Stooges, then like any good autodidact moved unsystematically into singles in various genres including garage psychedelia and surf. Successful hunch buys in those areas led to country and rockabilly then, eventually, New Orleans R&B.

“I didn’t know where a lot of it came from,” he says. “For years, I thought Specialty was a New Orleans label.” In all of it, he was looking for a few basic things. “Fire, riffs and beat,” he says.

The band for Jello Biafra’s New Orleans Raunch and Roll Revue includes labelmate Bill Davis on guitar with Pepper Keenan, Fred LeBlanc on Drums, Brian Broussard on bass, Josh Cohen on sax with the Egg Yolk Jubilee horn section, and Houston’s Pete Gordon on piano. The show starts at 9 p.m.