late 18th century, in the context of piracy: to walk along a plank placed over the side of a ship until one falls into the sea—hence, figuratively, early 19th century: to be forced to resign from one’s office or position
the earliest occurrences of ‘feet of clay’, used without explicit reference to the Bible, date from the French Revolution (1789-1799) and translate French ‘pieds d’argile’
nonsense, rubbish—USA, first decade of the 20th century—probably a euphemism for the noun ‘bullshit’, with the noun ‘dust’ used in the sense of ‘rubbish’, ‘garbage’
refers to a person who is ignorant or dismissive of the hardships of others—alludes to the phrase “let them eat cake”, attributed to Marie Antoinette, wife of King of France Louis XVI
to promote somebody to an ostensibly higher position where they will be out of the way and less influential—jocular variant of ‘to kick somebody downstairs’, meaning to eject somebody
USA, 1950, as ‘shopping-bag stuffer’—an advertising leaflet or similar piece of promotional material handed out to shoppers or placed in shopping bags alongside goods purchased