I can't reply to the original thread, but maybe starting a new one will work.
Knows what, "Well I Suwannee !!" means.
It means "I'll swear," and the quote is incorrect. It's actually, "I'll swannee," or "I'll swan." Swannee is the corruption of "Suwannee River" that Stephen Collins Foster used to keep the rhythm in his song, "Old Folks at Home." Nobody ever says "Suwannee."
Why "I'll swannee?" Because southern folks had a right proper fear of the lawd God, that's why. They knew it was sinful to use strong language, and they didn't want to bring the unbridled wrath of the God of the Hellfire and Brimstone Southern Baptists upon themselves by cursing (thereby cursing themselves). So rather than say, "I'll be damned," they said, "I'll swear." But even the use of that term was spooky and liable to danger, so they edited it a bit just to be sure the Lawd knew they weren't actually swearing. "I'll swear" became "I'll swannee."
A similarly G-rated substitution for a swear word, or curse word ("cussword" - let's pronounce it correctly, please) is "I'll vow," also once common throughout the south.
COMF