Oprah Winfrey will host a free farewell bash at Chicago’s United Center May 17 as the clock ticks down to the finale of her popular syndicated talk show (click at bottom to get tickets). Big-name actors and musicians will be brought out to surprise Winfrey and the 20,000-odd guests at the basketball arena. The gathering, dubbed Surprise Oprah! A Farewell Spectacular, will air in two parts, May 23 and May 24. The last episode of The Oprah Winfrey Show will air May 25. “As most of our viewers know, being surprised is not one of Oprah’s favorite things,” executive producer Sheri Salata said in a statement. “In the spirit of our farewell season, she is making a rare exception and we intend to make the most of that opportunity.” Tickets are available only through oprah.com. Winfrey, regarded as the most influential woman on U.S. television, is stepping down from her Chicago-based talk show to devote more energy to her fledgling cable network OWN, a joint venture with Discovery Communications.