Comes from the Latin root Mattus-La-Menacius, which was
lost in translation several times to become mo fo. Mattus-La-Menacius was a Roman Centurion /
dick sucker from 200 BC.
Legend has it that his descendance still lives on today in
the canadian city of Montreal. They headed overseas in the 18th century after being banned from their countries for indecent behaviour, which is supposedly still going on today.
Calling someone a mo fo is the worst insult, yet quite a compliment for Mattus-La-Menacius...
Love ya Matt