Title: Zing a Song "Would Go! rather have novocaine free dental surgery a la "Marathon Man" or spend an anesthesia-free evening listening to the saccharine harmonies of Rockapella? Let's see. Both would require a strait-jacket. Both would render us tearful and scarred. Both would require months of recuperation and, no doubt, therapy. Sounds like six of one and half a dozen of the other. But what do we know? Lots of folks love 'em! (Reminder: Lots of people love the WWF, too. Doesn't make it A-list entertainment.) At any rate, the bouncy, upbeat a capella quintet performs at the Somerville Theatre tonight at 8pm." By a Ms. Hayley Kaufman.