Not too happy with you using autism to call someone dumb, but I'll leave this up assuming it was just a one-off.
Definition of sash for Students. 1  1 : a frame for a pane of glass in a door or window. 2  2 : the movable part of a window.
My Chabad rabbi always puts on a black sash before praying. We joke that it is because he has attained a black belt in prayer arts. But seriously, what is the meaning of that sash? The black belt you refer to is called a gartel in Yiddish (similar to the English word girdle1).