Green’s Dictionary of Slang

chaffer n.1

[? SE chaffer, a bargainer, presumably about the price of commercial sex; or ? SE chaff, rubbish]

a sexual partner; the image is of quasi-prostitution.

[UK]Greene Mamillia II 229: Doest thou think Clarinda that I am so carelesse [...] as to choose such filthie chaffre, or so soone allured as to be in loue with such trash.