What are you thinking right now?

[Minty]

It has the same meaning over here as in Oz!

Although perhaps I ought to qualify that, the context of it being used as a word meaning a ninny comes from "Mansfield Park", specifically its main character Fanny Price who proved to be unpopular with the public for being so mousy (indeed the Famous Five's Aunt Fanny was specifically named as such as a literary joke). The "other" meaning comes from another novel, "Fanny Hill (Memoirs Of A Woman Of Pleasure".

Every day at SF an education in the utterly pointless!