"What are we talking about?" Dick Smothers asked brother Tommy at Wolf Trap last night. The question--a totally reasonable one given the circumstances--came during one of the many impossibly convoluted discussions the two had in their all too brief performance.

A reasonable answer, of course, was not in the cards. With Tommy often playing a guitar-strumming Gracie Allen to Dick's bass-plucking George Burns, non sequiturs reigned supreme. Logic was turned inside out and sibling rivalry never seemed like so much fun.

Still quarreling after all these years, the brothers haven't lost their touch for comedy. They made even the most familiar material--the "impossible dream" duet, for instance--seem totally spontaneous. And when playfully caustic remarks weren't prompting chuckles (Tom to Dick: "You have the easy assurance of the unconsciously ignorant"), inspired moments of musical madness worthy of Victor Borge were generating gales of laughter.

The Fifth Dimension ("We knew them back when they were the First Edition," cracked Tommy) closed the show. Unfortunately, the group was hampered by an uneven sound mix and inadequate preparation. At best, the quintet, sans two of its original members, created reasonable facsimiles of its numerous hits.