I am studying Roald Dahl's The BFG and I am confused by a couple of passages.
Context: The Big Friendly Giant suggests that the soldiers leave the helicopter and then drive Jeeps to man-eating Giants' sleeping place.
...the BFG told him, ‘But if you is taking these sloshbuckling noisy bellypoppers any closer, all the giants is waking up at once and then pop goes the weasel.’ (p.179)
And
Context:The Big Friendly Giant refused to tell the Queen the whereabouts of the Giant Country.
‘No, Majester,’ the BFG said. ‘Not on my nelly.’
I searched online. I found that "weasel and stoat" is rhyming slang for "throat". Is it correct to think that the soldiers' throats will be gone if the Giants are awake? And is ‘Not on my nelly’ a word play for "Not on your life?"
Could you please help me work out the meaning of these two phrases?