Green’s Dictionary of Slang

rug adj.³

In phrases

all rug (adj.)

(UK Und.) everything is secure.

c.1698		B.E. Dict. Canting Crew It’s all Rug, c. the Game is secured.
1714		T. Lucas Lives of the Gamesters (1930) 176: His great dexterity, of making all Rugg at Dice, as the cant is for securing a die between two fingers.
1725		in Anon. New Canting Dict. [as B.E.].
1737, 1759, 1760, 1776		, , , in Bailey Universal Etymological English Dict. [as NCD 1725].
1785, 1796		, in Grose Classical Dict. of the Vulgar Tongue n.p.: It is all rug, all right and safe, the game is secure, (cant.
1809		in G. Andrewes Dict. Slang & Cant.
1811		in Lex. Balatronicum.
1823		in Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict. 28: Rugg - all right and safe.
1848		in Flash Dictionary in Sinks of London Laid Open [as Kent 1835].
1859		in Matsell Vocabulum.