Ginger up

To ginger up a person is to infuse mettle or spirit into them and dates from the early 19th century. It derives from the rather unpleasant practice of putting a piece of raw ginger rhizome up the anus of a horse to liven up the animal and encourage it to carry its tail high. Horses were regularly gingered up in this way at horse shows during the 18th century, perhaps they still are. There is no record, however, of this practice on humans except of course in the aforementioned figurative sense.