Pour half a cup boiling water into a mug; add a fingerpicking acoustic guitarist. Stir in a teaspoon of brown sugar and a tablespoon of butter. Cue bass line, plucked on a standup. Stir in a couple ounces of rum, and top off with equal parts mandolin and banjo players. Sprinkle nutmeg, vocals on top; garnish with slide guitar or fiddle if desired. Wonderful—you’ve just scalded the band Hot Buttered Rum and then doused them with liquor in a cheesy recipe metaphor. Just let them play bluegrass on Saturday, July 7, at the Osher Marin Jewish Community Center. 200 N. San Pedro Road, San Rafael. $20 nonmembers. 7pm. 415.491.1235.