rap, v.² — Green’s Dictionary of Slang

rap v.²

[? SE rap, to seize or snatch]

to swap, to exchange, to barter.

c.1698		B.E. Dict. Canting Crew n.p.: Rap to Swop or Exchange a Horse or Goods.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.