Green’s Dictionary of Slang

crap n.2

[Du. krap, cramp or clasp]

the gallows; thus knock down/up for the crap, to sentence to be hanged.

[UK]G. Parker Life’s Painter 137: He was knocked down for the crap the last sessions.
[UK] ‘Flash Lang.’ in Confessions of Thomas Mount 19: Knocked down upon the crap, condemned.
[UK]Vaux Vocab. of the Flash Lang.
[UK]Lytton Pelham III 298: A square crib, indeed! aye, square as Mr. Newman’s courtyard – ding boys on three sides, and the crap on the fourth!
[UK]Lytton Paul Clifford III 126: I’ll go to the crap like a gentleman, and not peach of my comrades.
[US]T. Haliburton Letter-bag of the Great Western (1873) 105: You are too fond of drink, and keeping company with needy mizlers to kepe secrets for any wun without bringing him to the crap.
[US]Monteleone Criminal Sl. (rev. edn).

In compounds

crap-merchant (n.) [merchant n.]

(UK Und.) the hangman.

[UK]G. Parker Life’s Painter 155: The world vulgarly call him the hang-man, but here he is stiled the crap-merchant.
[UK]Morn. Post (London) 8 Nov. 3/4: A Beggar’s Opera. Crispin Heeltap— [I] am sincerely glad I escaped the Beak and the Crap Merchant.