Green’s Dictionary of Slang

1. ‘nobody can mess with this’, a slogan used by the Mexican gangs of Los Angeles, often abbr. as c/s and written, as a graffito, after the gang’s name.

1974		Fuentes & Lopez Barrio Lang. Dict. 35: con safos Same to you.
1993		L. Rodríguez Always Running (1996) 46: The front door had ‘Los Lomas’ spray-painted on the outside, followed by the words ‘Con Safos’.

2. a general term of approval [note latterly used as a magazine title].

1974

Fuentes & Lopez Barrio Lang. Dict. 43: con safos magazine Popular Chicano magazine.