In “Laughter and Reflection,” comic legend Carol Burnett reprises the classic off-the-cuff banter she engaged in weekly on her smash CBS variety show decades ago. “I love the spontaneity of these evenings,” Burnett says. “I never know what anybody is going to say or do or ask, so it keeps me on my toes.” Beacon Theatre, 2124 Broadway at 74th St. Sep. 16-17, 8 p.m. Tickets are $59.50-$179.50 at beacontheatre.com.