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'Isn't she slightly strange, your aunt? 'Oh, she's as nutty as a fruitcake.'(CIDI)
Do I know Karl? Yes, I do. He's nutty as a fruit cake!(W.Magnuson,Eng.Idioms)
They had been above 8000 metres for several days and Steve recalls being as nutty as a fruitcake. (BNC)
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