To stimulate sexually with one's tongue. Earliest origins are traced to the mouth of the RumblePig.

When you eat dirt for the first time and leave your family to build a shack in the woods

To lick furiously with intent to stimulate or destroy. Usually tongue jacking is done to the asshole, cooter, or nuts.

verb.
The act of licking with great enthusiasm, so much that it appears as if the licker is attempting to lift the entire body weight of the lickee using only the tongue.
Analagous to a floor jack lifting a car.
Used for describing the act of cunnilingus or analingus, or non literally as an eager ass kisser or brown noser.

To aggressively lick or kiss a person.