Green’s Dictionary of Slang

(US prison) N, the 14th letter of the alphabet; the ref. is to gangs from North California.

1998

Mayor’s Anti-Gang Office City of Houston, TX Street Gang Sl. / Gloss. 9 Nov.: 14 or XIV or X4 Fourteenth letter of the alphabet ‘N’; refers to allegiance to Northern California or Norte Califas gangs.