In Europe, it is in many countries the
short form of fashist.
In Germany, for instance, "ein Fascho" translates to "a fashist", or "das ist aber fascho" (eng. "that is so fashist"). Even Google Translator translated "Er ist ein Fascho" into "He is a fascist", and equivalent to "fascho" (adjective).
It is, however, not related to the
American Black
slang of "fasho" as "for sure".