A fannyknuckle is a female who is a very manly lesbian. Fannyknuckle lesbians usually look like men and pretend that they are rock solid. Usually have a very feminine lesbian accompanying them. The opposit male version of a fannyknuckle is a dickfeather.
Woman 1: Wouldn't it be great to have a dick
Woman 2: Has anyone ever told you your a bit of a fannyknuckle