The new slang sense of north from the 1800s on, meaning strong, where drinks were concerned, came from the Navy. Grog that was due north was absolutely neat, no water in it at all. Too far north–desperately, incapably drunk–now carried the sense of being hopelessly lost up there in the ultima Thule of booze. Elaborated into a jovial saloon-bar or shipboard witticism, it even brought together the degrees proof of spirits with the degrees of north latitude. Another point north, Steward: mix that a bit stronger, won’t you?
–Francis Spufford, I May Be Some Time: Ice and the English Imagination