Green’s Dictionary of Slang

(Aus./UK Und.) the stealing of washing, usu. women’s underwear, from where it is hanging out to dry.

1839		W.A. Miles Poverty, Mendicity and Crime; Report 62: The trampers are generally thieves, purloining whatever they can from the dwellings, or stealing linen from the hedges [...] designated by them snow-dropping.
1840		Flash Mirror 6: Snow Hunting. — Going out after dark on the bye-roads, where there are many cottages inhabited by laundresses, &x., and robbing the lines of wet linen.
1846		Manchester Courier 17 June 5/1: Judy Quin [...] charged by Police-Constable B7 with [...] what is termed by ‘the profession’, snow-dropping, in other words, with having stolen a dress from a clothes line.
1857		‘Ducange Anglicus’ Vulgar Tongue 32: snow-dropping—stealing linen off a hedge.
1867		Mt Alexander Mail (Vic.) 23 May 2/4: ‘Snow-dropping’ is a slang term used by the criminal class of Victoria to indicate the robbery of linen left in yards to dry.
1868		‘Six Years in the Prisons of England’ in Temple Bar Mag. Nov. 536: ‘What do you mean by ‘snow-dropping?’ I asked ‘O!’ said he, ‘that’s a poor game. It means lifting clothes off the bleaching line, or hedges. Needy mizzlers, mumpers, shallow-blokes, and flats may carry it on.’.
1882		Sydney Sl. Dict. 9/2: Dick’s a broker, and has gone out snowdropping, and Chumpy is trying to fence a yack to a muff, or to play a skin game. Dick’s hard up, and has gone out to steal clean clothes (from clotheslines and hedges), and Chumpy is trying to sell a watch to a simple one, or to skin him at cards.
1884		Leics. Chron. 24 May 12/3: Shiney [...] became a regular spinnakin dosser. Then he took up snow-dropping.
1888		Shields Dly Gaz. 16 Jan. 4/2: [headline] ‘Snowdropping’ By A Willington Man.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.].
1931		‘English Und. Sl.’ in Variety 8 Apr. n.p.: Snow hunting—Taking washing from line.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xl 4/4: snow droppings: Stealing from clothes lines.
1999		G. Seal Lingo 36: snowdropping was stealing linen from a hedge or wherever it had been left to dry, a term that is still with us to describe a man who steals women’s underwear from clothes lines.
2020		‘[W]G. Disher Consolation 3: ‘[W]ho’d want to steal an old lady’s underwear?’ ‘It’s called snowdropping,’ Hirsch said.