Gyun-Woo (Cha Tae-Hyun) is a college student, more interested in picking up girls, drinking with his buddies and avoiding his nagging mother whenever possible. While riding the subway, a drunken girl (Jun Ji Hyun) then changes his fate forever. She's nearly unconscious on the train and vomits on an older guy. She then leans over to Gyun-Woo and everybody assumes she is his girlfriend! Gyun-Woo soon finds himself in a relationship he didn't ask for, but soon unable to forget this sassy girl.