Green’s Dictionary of Slang

a miserable or dour face; thus Friday-faced adj., miserable, gloomy.

1599		Shakespeare Much Ado About Nothing V iv: Good morrow Benedick. Why, what’s the matter, That you have such a February face, So full of frost, of storm and cloudiness?
1606		Wily Beguiled 57: Marry out upon him: what a Friday fac’t slave it is! I think in my conscience, his face never keepes Holiday.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Friday face, a dismal countenance, before and even long after the reformation. Friday was a day of abstinence or jour maigre.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1834		‘Jack Downing’ Andrew Jackson 158: These were instantly made tu put on their Friday face and were put tu bed with a shovel tu save future mischief.
1859		Matsell Vocabulum.
1864		London Standard 13 Dec. 3/2: ‘Friday face,’ a dismal visage .
1873		Sl. Dict. 169: Friday-face a gloomy-looking man. Most likely from friday being a day of meagre fare among Cathlics and High Church Protestants.
1881		Trumble Sl. Dict. (1890).
1900		B. Runkle Helmet of Navarre 198: And there is small need to look so Friday-faced about it. If I have denied you one lover, I will give you another just as good.
1915		M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 218: Friday-faced, gloomy. ‘Why so Friday-faced? Trouble must have been brewing.’.

(W.I.) a timid person.

1996

Allsopp Dict. Carib. Eng. Usage.

(Can./N.Z.) never, that is very unlikely, ‘that’ll be the day’.

1988		McGill Dict. of Kiwi Sl. 112/2: that’ll be the frosty Friday/frozen fortnight Kiwi variants of ‘that’ll be the day’.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].