Sung Si Kyung who is well known for his soft voice and gentle image appeared on Running Man. Sung and another guest Kim Dong Hyun, a UFC player, run with a mission of 'Golden Key Race' to receive higher dividends. Sung Si Kyung, Kim Dong Hyun, Haha Sung was obviously flustered because nobody say hello before shooting the show. Yoo and Kim Jong Kook teased him saying, "You are too accustomed to studio variety shows. In outdoor show, appearance itself is a greeting." Yoo Jae Suk said, "Yoo…