Green’s Dictionary of Slang

n.m.c. n.

[abbr. no mates club]

(UK juv.) a metaphorical ‘club’ whose members are the least popular children at school.

OnLine Dict. of Playground Sl. 🌐 n.m.c. Acronym for ‘no mates club’. A member of the nmc describes one without any friends. A ‘president’ is someone with absolutely and utterly no mates. Member of nbnmc = ‘nasty bastard no mates club’ describes someone who espouses to have chosen to have no mates because he’s a nasty bastard.