USA, 1978—to commit suicide; to demonstrate unquestioning obedience or loyalty—alludes to a mass suicide, in 1978, by members of the Peoples’ Temple in Jonestown, Guyana, who drank a cyanide-laced drink thought to be similar to Kool-Aid
USA, 1957—the rhythm method of birth control, as permitted by the Roman Catholic Church—with allusion to the unpredictable efficacy of this contraceptive method: from ‘Vatican’, denoting the authority of the Roman Catholic Church, and ‘Russian roulette’
meaning: ‘what is appropriate in one case is also appropriate in the other case in question’—earliest occurrence in A Collection of English Proverbs (1670), by John Ray
1793—probably ultimately after post-classical Latin ‘mille viae ducunt homines per saecula Romam…’ (‘a thousand roads lead for ever to Rome the men…’)—the metaphor occurred in A Treatise on the Astrolabe (ca 1391), by Geoffrey Chaucer
American English—1902: bare feet (used of Doukhobors, i.e., members of a Christian sect that originated in Russia, many members of which emigrated to Canada in the late 19th and early 20th centuries)—1965: open-toed leather sandals of a simple or functional style (used of young persons)
UK, 1772—a holiday period of thirteen days, from Monday to the Saturday of the following week, humorously regarded as the longest holiday available to a parson who was excused one Sunday’s duties—later also: a holiday period of six days, from Monday to the Saturday of the same week
‘to sleep in Mother Greenfield’s’ (tramp slang): to sleep out in the open fields—‘to worship under Dr. Greenfield’: to go for a walk in the countryside rather than to attend a religious service
1809—a transient light preceding the true dawn by about an hour, a phenomenon common in Eastern countries—translates Arabic ‘ṣubḥ kāḏib’—figuratively: a hopeful sign that can prove either illusory or authentic
1580—always having to be ready to obey someone’s orders immediately—‘beck’ denotes a mute signal or significant gesture (such as a nod or a motion of the hand), indicating assent or notifying a command