"Nuck Figgers" was originally the name given to a community of European-born Canadian
people who lived on the island of Nuck, just off the northern coast of the province of Manitoba,
Canada. These
people largely lived off the land, harvesting crops. And since the only crop on Nuck was figs from
fig trees, they made everything out of figs. Their
food was figs, their clothing was figs... Everything was figs. And hence, they became known as the Nuck Figgers.
As you'd expect from such an isolated island community, though, the Nuck Figgers were terrible racists. They'd accept white outsiders into their community (as
long as they liked figs), but as soon as a black man came around, they'd mob up to tear him limb from limb. This continued until the more progressive-minded children of their
parents got tired of hating
people with other skin colours and left Nuck forever. The Nuck Figgers community died out in 1973, the last dying of malnutrition at 81.
However, the
legend of the Nuck Figgers lived on. So fierce were they in their hatred of dark-skinned individuals, that "Nuck Figgers" became a byword for hostility towards black
people. Even today, calling out "Nuck Figgers" will scatter any African-descended persons around, as it indicates to them that you are willing to act in the manner of the Nuck Figgers of old, and so they will be unwelcome around you.
The fact that the words "Nuck Figgers" are a spoonerism for an expression involving the N-word is just a coincidence.