A drink that has been secretly drugged, or in other uses, a deceptive trick; also the name of a mouse character.
Unknown origin; 'slip someone a micky' or 'micky finn' appeared in American slang in the early 1900s. The origin of the name is debated among etymologists.
The phrase 'slip someone a micky' is a dark piece of slang from prohibition-era America, and while we don't know exactly where 'Micky' comes from, the fact that it survived into modern English shows how criminal slang sometimes becomes standard vocabulary.
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