To WAP,
to lie with a Man. If she won't wap for a Win, let her trine for a Make; if she won't lie with a Man for a Penny, let her hang for a Half-penny. Mort wap-apace; a Woman of Experience, or very expert at the Sport.
To Wap in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).