'The kitchen sink ' = the last item of all possible items , and the normal phraseology is t o throw/try/eat/gather/buy/build/etc everything but the kitchen sink . The kitchen sink itself is an arbitrary but jocular choice for this idiom: it is a large, awkward and immovable item that normally is used for nothing other than washing dishes. Throwing more than the kitchen sink is, to me, a neologism-- a bit of hyperbole on the traditional idiom.
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