to refuse to face up to unpleasant or awkward realities—refers to the practice traditionally attributed to the ostrich of thrusting its head into the sand when being overtaken by pursuers, supposedly through an incapacity to distinguish between seeing and being seen
1607, as ‘as snug as pigs in pease-straw’—especially in ‘(as) snug as a bug in a rug’, phrases built on the pattern ‘(as) snug as [animal name] (in —)’ mean ‘in an extremely comfortable position or situation’
1922—‘like death warmed up’ (also ‘like death warmed over’): extended form of ‘like death’, attested in the mid-17th century and meaning ‘extremely ill’, or ‘exhausted’
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
increasingly strange—alludes to Alice’s Adventures in Wonderland (1865), by Lewis Carroll—first occurs from 1878 onwards in novels by Margaret Wolfe Hungerford
1762: the time of night when it is said that witches are active and supernatural occurrences take place—alludes to ‘the witching time of night’ in Shakespeare’s Hamlet—also (1985): the last hour of trading each month when exchange-traded stock options expire
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