A girl that enjoys anal sex, sometimes even over vaginal sex. This is usually a secret preference, and not advertised by the girl, to avoid jokes and to protect her "reputation" as a "nice" girl.
She'llnever admit it, but I've heard that she's a Backdoor Betty!
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