Green’s Dictionary of Slang

1. spectacles, eye-glasses.

1567		R. Edwards Damon and Pithias (1571) Fiiii: They be gay Barnikels, yet I see neuer the better.
1696		Motteux (trans.) Gargantua and Pantagruel (1927) II Bk V 610: And thus sleeping, they had barnacles on the handles of their faces, or spectacles at most.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Barnacle [...] a nick name for spectacle.
1812		Vaux Vocab. of the Flash Lang.
1822		(con. early 17C) W. Scott Fortunes of Nigel I 21: Give me the barnacles, my good youth, and who can say what nose they may bestride in two years hence?
1830		Egan Finish to the Adventures of Tom and Jerry (1889) 309: Likewise to Jerry Hawthorn, Esq., I bequeath my four-eyes, my barnacles, my green-specs, but, amongst opticians, denominated spectacles.
1841		A.M. Maxwell Run Through the United States I 96: A certain Mr. John Pease, a notorious horse-dealer, came forward with barnacles on nose.
1849		Sam Sly 24 Mar. 3/2: He advises [...] his carrotty-headed brother not to wear barnacles in the streets.
1852		F. Smedley Lewis Arundel 97: I did not recognise you one bit, till you pulled off the barnacles.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1866		Letters by an Odd Boy 164: ‘Barnacles,’ is a corruption of bino-cula.
1884		‘’Arry at a Political Pic-Nic’ in Punch 11 Oct. 180/1: A sniffy young Wiscount in barnacles.
1895		Crowe Aus. Sl. Dict. 6: Barnacles [...] spectacles.
1896		G.F. Northall Warwickshire Word-Book 22: Barnacles. Spectacles.
1912		E. Pugh City Of The World 271: A nice old benevolent party in gold barnacles and a hat that is called a wideawake.
1923		M. Garahan Stiffs 44: Ain’t he a hard case, him and his ruddy barnacles.

2. (UK Und.) fetters, irons; latterly handcuffs.

c.1698		B.E. Dict. Canting Crew n.p.: Barnacles, the Irons Fellons wear in Gaol.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1750–1882		B.M. Carew Life and Adventures.
c.1850		Duncombe New and Improved Flash Dict.
1859		Matsell Vocabulum 10: barnacles [...] hand-cuffs.
1881		Trumble Sl. Dict. (1890).
1895		Crowe Aus. Sl. Dict. 6: Barnacles, handcuffs.
1901		Argus (Melbourne) 20 Sept. 6/4: Sometimes [...] the operator in coin has a serious check, the first stage of which is either cramp rings, bracelets, barnacles, darbies, or irons — all of which are just handcuffs.
1973		(ref. to 1890s) ‘Gloss. of Larrikin Terms’ in J. Murray Larrikins 201: barnacles: handcuffs.
1999		G. Seal Lingo 44: Frequently it was difficult, if not impossible, to distinguish between the lawful and the lawless, a difficulty that saw many larrrikins [...] brought in barnacles (handcuffs) before the beak (magistrate) and taking a little air and exercise inside.

3. (US) spots, pimples.

1842

Wkly Rake (NY) 3 Sept. n.p.: Lor pa! what’s them red things you has on your nose?’ ‘Pimples, child [...] Barnacles’ .