To tread in a surreverence, to be bewrayed: an allusion to the proverb, Sh-tt-n luck is good luck.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Lubber * Lud’s BulwarkNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes