Plural of doohickey; multiple small gadgets or objects whose names are forgotten or unknown.
Simply the plural form of doohickey, formed by adding the standard English -s suffix to indicate more than one unnamed object.
The plural of a nonsense word is still a nonsense word, but it's perfectly grammatical—language lets us apply the rules we know to made-up words, which is why even speakers hearing 'doohickeys' for the first time understand it means 'multiple doohickeys.'
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