Green’s Dictionary of Slang

bullock(’s horn) v.

to pawn.

1873		Sl. Dict.
1897		‘Doss Chiderdoss’ ‘Meg’s Diversion’ Sporting Times 4 Sept. n.p.: For she’d an empty sky, And nothing to bullock’s horn.
1957		G. Kersh Fowlers End (2001) 268: My daisies I bullock’d for two pig’s ears / To warm my Auntie Nelly.
1960, 1975		Wentworth & Flexner DAS.
1981		P. Wright Cockney Dialect and Sl. 107: To bullock’s ’orn [...] means to ‘pawn’, but normally an article is just bullocked.