"..."Sweet san fairy ann" is what I hear in the Kingston Trio recording, but what it means has been a puzzle to me for 30 years. ..." -Joe Offer-

LOL
I've always heard that line as "Oh, how the sweet Sam Perry, Anne, do I know who you are ... ?!" LOL

Since I never expected my audiences to understand that line, I've always changed it to:
"Oh, how the bloody devil, Anne, can I tell who you are ...?"