This might not be what you are looking for exactly , because allegedly, it's still the same 'language',.... but,
Online Etymology Dictionary -
''FANNY''
"buttocks," 1920, Amer.Eng., from earlier British meaning "vulva" (1879), perhaps from the name of John Cleland's heroine in the scandalous novel "Fanny Hill or Memoirs of a Woman of Pleasure" (1748). The fem. proper name is a dim. of Frances.
The genital sense is still the primary one outside U.S., but is not current in Amer.Eng., which can have consequences when U.S. TV programs and movies air in Britain.