Lee Si-yeon

Eun-sik tries to pass the state exam while studying in college after his military service. One day, he meets a beautiful woman Eun-hyo, and his life changes.

In his 10th year at college, Eun-sik is part of a nearly ideal campus couple with swimming champ Kyung-ah. While their three-year relationship is solid, Eun-sik struggles to get to the next level with Kyung-ah; despite the help and support of his friends, he can't manage to get her into bed.

When a young gang leader seems to be just a bit too stupid to effectively carry out his daily tasks, his superiors order him to go back to school for his high school diploma. Posing as a 19-year-old, he soon learns that the school is even more corrupt and vicious. Wrath is unleashed.

Struggling artist Min Hee-do is offered three billion won to bet his life to a game against a rich old man, Kang No-sik, who is dying from a terminal illness. The game is for each man to dial a random phone number and guess if the person who answers will be male or female. Hee-do loses the bet, and after a month long brain operation, he wakes up to find that they have swapped bodies.

Celebrity guests are split into two teams to compete in various contests. One guest, known only to himself, is designated the "X-Man", and does his best to cause his team to lose the contests. At the end, all guests try to determine the X-Man's identity.