high muckamuck: important or self-important person
Also spelled muckymuck and muckety-muck. This facetious term for a higher-up first began appearing in print in the 1850s. Linguist Charles Lovell, writing in the April 1947 American Speech, suggests that the term comes from Chinook Jargon hiu muckamuck, which roughly translates as 'plenty to eat'. Lovell argues that the term was in use out West as slang for a big shot, with hiu being misinterpreted and eventually standardized as English high.
People have always used muckamuck as a mild form of ridicule, either to show a lack of awe toward someone in charge or to puncture the pretensions of people who aren't as important as they think they are. Part of the entertainment value probably derives from the negative connotations of muck. An early example appears in the Sacramento Union for December 28, 1861: "We desire to call the attention of the 'high muck-a-muck' of the telegraph to the condition of the lines over the mountains." More recently, the following headline appeared in the San Antonio Express-News for November 10, 2001: "That was no lady, that was a high City Hall muck-a-muck!"