At this year’s Hardly Strictly Bluegrass Fest, Primus fans were stoked to see Les Claypool’s latest side project, Duo de Twang, a twisted, honky-tonk acoustic duo with Mirv, aka Marc Haggard. (Earlier that week, at Terrapin Crossroads, the pair had busted out a fun, stripped-down version of ’90s Primus hit “Jerry Was a Race Car Driver” to the delight of the crowd.) Duo de Twang joins Bob Weir and Jackie Greene for a show at 142 Throckmorton this week, with proceeds going to Casa de Milagros, a Peruvian orphanage. Money will also be donated to J/P Haitian Relief Organization, which works to bring sustainable programs to the people of Haiti. The fourth annual benefit show drives so goddamn fast on Thursday, Dec. 6, at 142 Throckmorton. 142 Throckmorton Ave., Mill Valley. 8pm. $125—$175. 415.383.9600.