One spring afternoon back in the Pleistocene Era, a wry, folkish Missouri duo fired up “One Toke Over the Line” on a Deep South university quad where the gathered students mostly were. Michael Brewer and Tom Shipley’s unlikely Top 10 hit put them on the campus circuit. VP Spiro Agnew called them “subversive.” A squeaky clean Lawrence Welk duo even sang the tune in the addled belief it was a “modern spiritual” due to its offhand “Sweet Jesus” reference. And nearly 50 years on, B&S are still trundling their deep, amiable catalogue along Tarkio Road in fine style. Vicky Emerson opens.