In band years, 12 is nearly a millennium. That the Grandsons have managed to survive that long may be because of the happy music they play—”The band that laughs together lasts together”? Whatever their secret, tonight they celebrate both their almost-one-eighth-of-a-century anniversary and the release of their third CD, Pan-American Shindig. To say that the disc is all over the map is to compliment the ‘Sons on their musical versatility and smart egalitarianism. They call it roots-pop, and Shindig cavorts brightly from Western swing and rockabilly to New Orleans-style R&B to Tex-Mex and mambo—always with smiling wit. In fact, after suffering unjustified cruelties at the ham-fisted hands of a legal system incapable of distinguishing a Son from a Grandson, the band turned what might have been a career-ending episode into perhaps the album’s most infectious track (which is saying something), the lilting “Son of a P#&*%%$!” Pioneering members Alan MacEwan and Chris Watling, ably assisted by current drummer Matt Sedgley, will be joined by past Grandsons, and perhaps a daughter or two, at 7:30 p.m. Sunday, Jan. 16, at the Barns of Wolf Trap, 1624 Trap Road, Vienna. $12. (703) 938-2404. (Dave Nuttycombe)