C/S... means "no backies"... when someone signs with con safos it means that whatever point has been made has been symbolically protected from backlashing and comebacks. Usually used by Chicanos to avoid the senseless situation of being challenged on something he/she truly believes in... Con safos!
El Pelon: Yo man, let's tag up this crazy mural!
Chango: Nel man, we can't. It has Con Safos (C/S). If you write on it you will be offending yourself!
El Pelon: Ah man! Well then let's go find some Minutemen to beat up!