I would say it was pronounced whoooer's knickers. - my mum doesn't use that kind of language either. However, I have heard her use the word knickers, but never as an expletive. More like "I'm going to take 6d off your pocket money for every pair of knickers I find under your bed." It never worked, I'm still untidy.
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When you don't even know who's in the team
S.Yorkshire/Derbyshire border
Up and down like a whore's knickers is the way I heard that one @Woodgreen .
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
It never worked, I'm still untidy.