Green’s Dictionary of Slang

1. to chat, to make small talk; thus yarding n. [image of chatting over the fence between two backyards].

1907		Sun. Times (Perth) 26 May 4/8: When you’ve yarded and yapped to the nippers, / When you’ve bawled jingioistical gas.
1965		W. King ‘The Game’ in King Black Short Story Anthol. (1972) 302: We did this grunting – with Glorie’s meaningless yarding between – till three-four A.M.

2. (US black, also yard on) to be sexually unfaithful [note play in someone else’s yard under yard n.² ].

1960		C. Cooper Jr Scene (1996) 36: She told him she didn’t like to yard on her man.
1972		(con. 1950s) D. Goines Whoreson 170: Have you been out yarding somewhere?