Why is a person called a 'Duffus' when they do something stupid?

Is there any history behind this? There is a region in Scotland where Lord Duffus ruled.
Update: Okay it is 'doofus' and not 'Duffus' Einstein.
Update 2: ‘Doofus’, coined c. 1960, appears to be a descendant of the much earlier Scots word ‘doof’, meaning a fool. ‘Doof’ itself may well be linked to the German adj. ‘doof’: dense, stupid, dull-witted. There is, despite this, no Yiddish origin, although some etymologists have suggested that there might be. There may also... show more ‘Doofus’, coined c. 1960, appears to be a descendant of the much earlier Scots word ‘doof’, meaning a fool. ‘Doof’ itself may well be linked to the German adj. ‘doof’: dense, stupid, dull-witted. There is, despite this, no Yiddish origin, although some etymologists have suggested that there might be. There may also be a link to the earlier (1910s) ‘goofus’, which also means fool and which itself comes from ‘goof’, another Scots word, meaning simpleton, clumsy fool or silly person. (Google)
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