A male mistress. Derived from the words "fancy man."
The exact equivalent of a mistress but a man. A male who sleeps with a married woman on a regular basis.
As in "My fannyman gives me better lovin than my husband," or "If that fanny m*fu*ker ever sets foot in my house again, I'll kill him!," or "you can fannymac me anytime baby."
A complete and utter twat, dickhead, plonker for whom the words 'fanny' and 'wanker' just dont elicit the right level of bastardness of said person by themselves but when put together it totally describes the person and their pointless existence.
A referee from Glasgow at an Old Firm Derby Game when "That ref used to go to St Mungos School, haw ref ya fannywanker the ball was out!"