Dictionary.com's Word of the Year is...
"strong drink, drink laced with chloral hydrate," by 1928 (perhaps 1890s), of unknown origin. Presumably named after someone, but the various stories about the name cannot be substantiated.
[origin unknown and richly conjectured, chiefly being fathered on various bartenders or saloon proprietors with names like Mickey Finn]
[potato sense probably by association with the common phrase Irish potato]