Ji-seok's libido wanes whenever he stands in front of a woman. One day, while sleeping alone in his friend Dong-cheol's house, the latter's drunk girlfriend Hye-eun mistook him for Dong-cheol and has sex with him. Dong-cheol sees them but instead of getting mad, he masturbates to them while watching. Hye-eun later became angry after learning that it was Ji-seok she had sex with, but when she finds out about his libido problem, she agrees to help him, which culminates in a swapping of partners between her and her boyfriend, and Ji-seok and his new girlfriend.
A drunk chick mistakes her boyfriend's friend for her boyfriend and fucks him. Her boyfriend sees them but instead of getting mad, he masturbates to them while watching. Later, the two guys swap girlfriends.