It means Fancy+Sexy.
Such term can be employed in a plattera of situations to display a mixure of class or finesse and sexiness at the same time.
Best written using a capital F and accompanied with a sparkle emoji.
V, Fanny Mist is when a woman doesn't wash her vag for days on end & it's so bad down there she develpos fanny mist. Fanny mist can be toxic to breath in as fumes can lead to choking. To prevent fanny mist all a woman has to do is wash her vag.
Adam was about to start eating Jackie out when he was struck by her fanny mist & taken aback by the fumes he says "Jackie you have fanny mist i think you need a shower"