Green’s Dictionary of Slang

1. linen.

1879		‘Autobiog. of a Thief’ in Macmillan’s Mag. (London) XL 500: We used to go and smug snowy (steal linen) that was hung out to dry.
1887		‘Dagonet’ ‘A Plank Bed Ballad’ in Referee 12 Feb. n.p.: I smug any snowy I see on the hedge, / And I ain’t above daisies and clobber.
1904		in Hackney Gazette 21 Sept. 3: ‘Harvesting snowy’ – stealing a wetline of clothes to pledge at the pawnbrokers.

2. see snow n.¹ (1b)