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
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
UK, 1824—thoroughly or perfectly right—‘trivet’: a metal tripod for a cooking pot or kettle to stand on—the phrase refers to a trivet’s always standing firm on its three feet
UK, 1860—very much, very intensely—‘billy-o’ occurs only in this phrase—it is apparently composed of ‘Billy’, pet form of the male forename ‘William’, and the suffix ‘-o’, used to form slang and colloquial nouns, adjectives and interjections
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
UK, 2005—the perceived indiscriminate and excessive use by the authorities of anti-social behaviour orders—apparently coined by Álvaro Gil-Robles, the Council of Europe’s Commissioner for Human Rights—‘Asbo’: acronym from the initial letters of ‘anti-social behaviour order’
UK, 1763—extremely quickly or suddenly—in all probability, the male forename ‘Jack’, pet form of ‘John’, typifies an ordinary man, and the surname ‘Robinson’ is a generic personal name
UK, 1928—of a public-house: very basic and lacking in comforts—refers to the former practice of covering the floor of a public-house with sawdust into which customers spat