The Brown Scapular was given to a humble Carmelite Monk, Saint Simon Stock in England more than 700 years ago. The Carmelite legend tells us that The Blessed Virgin Mary appeared to St. Simon Stock on July sixteenth during the twelfth century. She handed him the Brown Scapular and said “whosoever dies clothed in this shall never suffer eternal fire”. 
What does this really mean?
Just wearing the Brown Scapular does not mean you will directly go to Heaven. Our dear Blessed Mother will intercede for us if we have been faithful Catholics following the teachings of the Catholic Church. This means following all of the Ten Commandments. If we happen to fall into mortal sin at the time of our death and have been good and faithful Catholics, she will intercede for us before Our Lord Jesus Christ granting perseverance in the state of grace of final contrition. However, the promise will not be given to obstinate sinners who sacrilegiously use the scapular as an excuse for sin. Such unfortunate souls will rid themselves of the holy garment and die without the consolation of its promise.