Mara Salvatrucha

From Rap Dictionary

Mara Salvatrucha or MS-13 as they're called most of the time are gang started by Salvadorans & also consist of a lot of Honduran & Guatemalan members. MS-13 used to be called the Mara Salvatrucha Stoners but later dropped the end part and picked up the number 13 when they joined up with the Mexican Mafia. They represent the number 13 cause the letter M is the 13th letter of the alphabet and it stands for Mexican Mafia. They wear the colors blue and white which are the same colors and it's original members countries flag(the Salvadoran flag).