A yard. The cove was lagged for prigging a peter with several stretch of dobbin from a drag; the fellow was transported for stealing a trunk, containing several yards of ribband, from a waggon.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
See also the definition in Nathan Bailey's 1736 dictionary of canting and thieving slang.
Straw * StretchingNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes