A patch of hair grown on a lady in her private area just above the vagina (fu fu) in a moustache shape. Note you can get many variations such as a handle bar fustache or Hitler fuatache.
She has a fustache on her fanny she shaped herself.
(n) def. When a young, pre-pubescent boy and/or half-asian attempts to grow a mustache, only to be thwarted by their genealogical inability to grow any substantial amount of hair.