Green’s Dictionary of Slang

euph. for sexual involvement, intercourse.

1623		Shakespeare Comedies Histories, & Tragedies n.p.: Laf. So you were a knaue at his seruice indeed. Clo. And I would giue his wife my bauble sir to doe her seruice.
1721		‘Anodyne Tanner’ Elizabeth Wisebourn (1885) 4: [of a woman] [S]he soon contracted a very particular Friendship with several Ladies of the first Rank [...] for as she was at all times ready to serve them, they upon all Occasions made use of her Service.