It’s not so much found these days, though it is a delightful word for describing underhand practices or dishonest manipulation of individuals for personal profit. People also mean by it some form of trickery, especially the arcane manipulation required to make an item of technical equipment work the way you want it to (“most handsets need some jiggery-pokery to be Apple compatible”; “it may lead to copied games running straight from the DVD without the need for any further jiggery pokery”).
The charm of jiggery-pokery lies partly in its bouncing rhythm, a classic example of what’s called a double dactyl, a dactyl being a stressed syllable followed by two unstressed syllables; it’s named after the Greek word for finger, whose joints represent the three syllables. Other examples of double dactyls are higgledy-piggledy and idiosyncrasy.
The word appears at the end of the nineteenth century and is first recorded in Wiltshire and Oxfordshire dialect. The English Dialect Dictionary quotes an Oxford example, “I was fair took in with that fellow’s jiggery-pokery over that pony.” The experts are sure that it actually comes from a Scots phrase of the seventeenth century, joukery-pawkery.
The first bit of it means underhand dealing, from a verb of obscure origin, jouk, that means to dodge or skulk; this might be linked to jink and to the American football term juke, to make a move that’s intended to deceive an opponent (the other juke, as in jukebox, has a different origin). The second bit is from pawky, a Scottish and Northern English word that can mean artful, sly, or shrewd, though it often turns up in the sense of a sardonic sense of humour.