slip someone a Mickey Finn
slip (one) a Mickey (Finn)
To put a drug in someone's drink that will make them lose consciousness and incapacitate them; to serve someone a drink laced with such a drug. Please be careful—it's scarily easy for someone to slip you a Mickey at big parties like that. The victim of the robbery stated that the assailant had slipped him a Mickey Finn at the bar.
slip someone a Mickey FinnINFORMAL
If someone slips someone else a Mickey Finn, they give them a drink containing a drug that makes them go to sleep. I went there once and was slipped a Mickey Finn.
slip someone a Mickey Finngive someone a drugged or otherwise adulterated drink.
Recorded from the 1920s, this expression is of unknown origin, but it is sometimes said to be the name of a notorious Chicago barkeeper ( c .1896–1906 ).