It's true, believe it or not. The band were initially called The Sveltes, and then Wild Honey, but when they picked up[ a recording contract, producer George Perry's friend George Harrison suggested a change of name to Fanny. Because there wasn't the interchange of cluture between the US and the UK in the early 70's that there is now, it's quite possible that Perry and the band assumed that the band's name had the same meaning in Britain as in America - a harmless slang expression for a bottom, of either gender, and they were in blissful ignorance of the more gender-specific annatomy description conjoured up by the term over here. Who said George Harrison had no sense of humour?