Lee Kwang Soo had an embarrassing moment based on his age.
Choi Ji Woo appeared as a guest on SBS "Running Man" with Jung Yong Hwa, Lee Jong Hyun, Lee Ki Kwang and Simon D.
Yoo Jae Suk said, "I'll admit the other guests fit with F4, but not Simon D. If Gary wasn't here, Simon D would be their manager. You're one of us."
Simon D replied, "I'm still in my 20s." The "Running Man" members said, "we have a member that's still 20." Choi Ji Woo was shocked and asked, "who, who?"
She found out that Lee Kwang Soo was still in his 20s and was shocked. Lee Kwang Soo said, "I'm the youngest here, the youngest." Choi Ji Woo said, "no way. Wow, are you serious?"