PSY, Diana Ross to perform at 'Christmas in Washington' WASHINGTON, Nov. 29 (UPI) -- PSY, Diana Ross, Megan Hilty, Demi Lovato, Chris Mann and Scotty McCreery are to perform during the upcoming "Christmas in Washington" event, TNT said. Comedian and late-night chat-show host Conan O'Brien is to serve as host of the holiday special for a second consecutive year. The program will be taped Dec. 9 and will air Dec. 21. "Celebrating its 31st anniversary this year, 'Christmas in Washington' is a holiday tradition benefiting the Children's National Medical Center," a release said. The concert is attended each year by the president and first lady, as well as many other Washington VIPs. This will mark TNT's 14th year presenting 'Christmas in Washington.'