When a girl who seems shy at first and is almost every time changing the 'sex' subject when somebody mentions it. In reality she wants to bang almost every guy at any time. This is mostly refered to high school and college girls who seem shy at high school but break free and become an 'Instant pussy' at college.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi