Green’s Dictionary of Slang

rub-up n.1

[rub up v. (1)]

1. an act of sexual intercourse.

[UK]Partridge DSUE (1984) 994/1: from ca. 1620.
[UK]J. Cameron It Was An Accident 63: ‘Now I make the coffee,’ I went when the movie had finished. ‘Then we have a little rub-up?’.

2. masturbation.

[UK]Partridge DSUE (8th edn) 903/2: C.19–early 20.