The place I originate from, and I understand that the meaning is identical in Mexico, "chusma" is used to refer to "very low class" persons. The most effective English equivalent I can imagine is "riff-raff" Nos cuentas el origen de la expresión “dormir a pierna suelta” a quienes lo desconocíamos: https://keeganzsgbq.bloggin-ads.com/56679534/little-known-facts-about-chusma-ligar