Yi Enhui and Kim Jong Kook stem from a classic game "Of course! "Of course" game in Korean variety show X-Men. In this game, no matter what the other side says, both sides have to answer "of course!" " "To show respect and courtesy.

In a game, Yoon Eun Hye and Kim Jong Kook became a pair. At that time, Yoon Eun Hye challenged Kim Jong Kook that if Kim Jong Kook could make her laugh three times in a row in the game, she would win.

Kim Jong Kook accepted this challenge and began to make Yoon Eun Hye laugh in various humorous ways. However, Yoon Eun Hye never laughed, but became more and more serious. When Kim Jong Kook tried to make Yoon Eun Hye laugh for the third time, he suddenly covered Yoon Eun Hye's ear and said something loudly.

At this moment, Yoon Eun Hye burst out laughing and let Kim Jong Kook successfully complete the challenge. However, when Kim Jong Kook let go, Yoon Eun Hye's expression became very serious again. This scene became a classic "of course!" A passage in the game was widely discussed and imitated by fans afterwards.

In addition, because of this game, Yoon Eun Hye and Kim Jong Kook were later combined by fans into a CP group called "Grace Zhong Guo", which lasted for many years.