1) a girl who looks like a man, so because she has a fanny she is referred to as someone who has a fanny but looks like a man
2) stephanie, London, fits this description
omg, look at that fanny-man!!! shes bare butters!!
A girl that acts like a bloke.
Because they are not male, they cannot be a full man a 'dick-man' and, therefore, are the female version.
Girl: The footie last night was really good!
Boy: You're such a fanny-man