Abby,

"....BTW, we're still not quite sure, but the one mysterious line seems to be: 'how the sweet san fairy ann do I know who you are' which may or may not be WW I Englishified French, "ca ne fait rien" ('it means nothing.')

The existing discussion is at Mudcat discussion up to last year but still no actual authoritative text....."

What do you consider an authoritative text?
"San Fairy Ann/San Fairy Anna" certainly appears as an entry in "The Long Trail" by John Brophey and Eric Partridge with the above meaning (I can't lay hands on my copy at the moment or I'd quote the entry), but as Partridge was a professional lexicographer is this an authoritative source?.

Just found my copy of "Slang To-day and Yesterday", again by Eric Partridge (1st Pub 1933,1979 reprint ISBN 0 7100 6922 7).
"Sanfairyann. It doesn't matter! Why worry?! G.W.+. French ça ne fait rien."

Walrus