UK, 1836—a person, country, etc., that appears powerful or threatening but is actually weak or ineffective—from Chinese ‘zhǐlǎohǔ’ (‘zhǐ’, paper, ‘lǎohǔ’, tiger)—used in the post-war years by the Chinese Communist Party of the USA and other reactionaries
1909 to 1923 in stories by English author P. G. Wodehouse—a facetious appellation for a home or hospital for people with mental illnesses—‘loony’: shortened form of ‘lunatic’
USA, 1889—when a situation reaches a critical point and one must commit oneself to an action or decision—the image is of having to shove when mere pushing is ineffective
American English—a surge of extremely cold air which causes rapid falls in temperature and severe wintry weather in central and eastern areas of the United States and Canada—after ‘Trans-Siberian Express’, the name of a railway running from Moscow to Vladivostok on the Sea of Japan
UK, 1808—to make one’s beliefs or intentions plain—from the former practice of nailing an ensign to the mast of a ship, after damage during battle resulted in the ship’s colours no longer being clearly displayed, which otherwise might have been interpreted as a signal of surrender
USA, 1917—a method of treating a drug addict by sudden and complete withdrawal of the drug, instead of by a gradual process—alludes to the goose pimples, resembling the skin of a cold turkey, that a person experiences as a side effect of the treatment
UK—‘the Beast from the East’ (2011): polar continental air mass, which brings wintry conditions—‘the Pest from the West’ (2012): mild air from the Atlantic, which brings strong winds and heavy rainfalls
USA, 1857—an exclamation expressing surprise or dismay—the motivation for the choice of the female forename ‘Betsy’ (variant of ‘Betty’, pet form of ‘Elizabeth’) is unknown
USA, 1775—to do or say something remarkable or startling—the precise underlying notion in the choice of ‘Dutch’ is not clear—‘Dutch’ occurs in a number of derogatory or derisive English phrases