Green’s Dictionary of Slang

snapps n.²

also snaps, snops, snopsy

[Ger. Schnaps]

Dutch gin, genever.

1864, 1867, 1870		Hotten Sl. Dict.
1890–1904		Farmer & Henley Sl. and Its Analogues VI 285/2: Snopsy (Snops or Snaps) [...] American.— Gin (i.e., Schnaps).