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This question had a sequel to the question just below. The meaning of 'blow me down'
Thanks to WS2's reply and link I draw my conclusion for the phrase 'blow me down.' But to my surprise I think I have reached a different answer than you.
Here are examples that you presented in your link.
- I'm absolutely blowed if I know what to do.
I think this sentence means that I would be shocked if I know what to do. That is, I think I have no chance of knowing what to do.
- Blow me tight if ever I saw such a thing in my life before.
I would be shocked if I saw such a thing in my life before. There's no chance of my seeing such a thing in my life before. That is, that's my first time that I saw such a thing in my life.
- Blow me if I do!
I would be shocked if I do. That is, there's no chance that I do (it).
Am I right in my description of the three sentences above?
And on the sentence in question, I draw my comprehension based on your explanation.
- "Blow me down if she didn’t just run off!"
I would be shocked if she didn’t just run off! There's no chance that she didn’t just run off. That is, she must have just run off. If not, I would be shocked.
The last line is my conclusion that I drew on your explanation.
Here is your sentences. "When she just ran off, you could have knocked me over with a feather!" "She's run off ? - well blow me down!"
These two sentences implies that I am shocked because she runs off. That means the speaker didn't expect she would run off. If that is your thought, that's just the opposite of mine.