A person who uses cocaine, or someone who works with coke production.
From 'coke' + '-ie' (diminutive/informal suffix). The drug-use sense emerged in 20th-century slang; the industrial sense is older and now obsolete.
The '-ie' suffix is how English speakers make informal, nickname-like versions of words—'birdie' from bird, 'sweetie' from sweet. 'Cokie' could be affectionate (your buddy at the coke plant) or derogatory (calling someone by their drug habit), depending on context and era.
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