high muck-a-muck
Concise Oxford English Dictionary © 2008 Oxford University Press:
high muck-a-muck (also high muckety-muck)
▶noun N. Amer. informal a self-important or conceited person.
– origin C19: perh. from Chinook hiyu ‘plenty’ + muckamuck ‘food’, with high substituted for hiyu.
'high muck-a-muck' also found in these Oxford entries:

