UK, 1985—to be ‘stale’, to be no longer innovative, relevant, or effective—refers to the practice introduced in Britain in the early 1970s of stamping perishable goods with the latest date by which they may be sold
UK, 1805—personifies France or the French people, or designates a typical Frenchman—composed of ‘Johnny’, a pet form of ‘John’ used, with modifying word, to designate a person of the type, group, etc., specified, and of French ‘crapaud’ (a toad)—coined by British sailors during the Napoleonic Wars
UK, 1830—‘Jenny Darby’, ‘Johnny Darm’, and variants, were originally opprobrious names for any member of the new Metropolitan Police introduced in 1829 by Robert Peel—alterations of ‘gendarme’, with full or partial folk-etymological remodelling variously after the female forename ‘Jenny’, the male forename ‘Johnny’, and the surname ‘Darby’
UK, 1925—the verb ‘Adam and Eve’ is rhyming slang for ‘to believe’—there is no truncation, contrary to the usual rhyming-slang formation (cf. ‘scooby’, rhyming slang for ‘clue’, which is short for ‘Scooby Doo’)
UK, 1831—used when the result of a contest or the outcome of an action appears certain—originally used of horse racing—the noun ‘shouting’ denotes a loud and enthusiastic show of appreciation
UK and USA, 1816—to tell a long, far-fetched story—of nautical origin? (perhaps alludes to making ropes from lengths of yarn on board ship: the men would have told one another stories while performing this long and tedious task)
1758—humorous exclamation expressing surprise, excitement, etc.—‘star’: a badge in the shape of, or ornamented with, a star, worn as part of the insignia of an order of knighthood or of chivalry—‘garter’: the badge of the highest order of English knighthood, i.e., the Order of the Garter
Ireland, 1809—the Wednesday before Easter—refers to the day on which Judas Iscariot formed the intent to betray Jesus—‘spy’ denotes ‘one who spies upon, or watches, a person or persons secretly’, because, from Wednesday onwards, Judas Iscariot secretly sought an opportunity to deliver Jesus to the Jewish authorities
1747—a small outlay or risk ventured in the hope or expectation of a significant return—a metaphor from fishing, in which sprats are used as bait to catch larger fish—in early use with the words ‘salmon’ and ‘herring’ instead of ‘mackerel’
Scotland, 1806—to make a determined effort to achieve something, whether ending in success or failure—refers to the making of spoons out of the horns of cattle or sheep, which was common in Scotland till late in the 19th century