Green’s Dictionary of Slang

kneesies n.

also kneesie

1. (US) amorous knee contact, usu. covertly under a table; also in fig. use.

[US]T. Capote Breakfast at Tiffany’s 58: I let him play kneesie under the table.
[US]K. Marlowe Mr Madam (1967) 168: When we sat next to each other we’d play kneesies.
[US]B. Rodgers Queens’ Vernacular 121: kneesies [...] 2. fondling a person’s leg beneath the table undetected by other guests. Other games of this ilk are handsies, nosies and toesies.
[US]H. Selby Jr Demon (1979) 54: They [...] played a little kneesies and pinch assie under the table.
Hanson & Muchmore Coming Out Right 31: Don’t grope anybody, rub thighs, hold hands, play footsy or kneesies.
J. Kaye Stars Screaming 285: She was there, on the deck, drinking rum drinks and playing kneesies with that old man.
A. Marston Yesterday’s Spring 79: That luscious blonde sitting ringside and playing kneesies with her pretty boy escort.

2. in fig. use.

[US]H. Carlton Sacrifice 420: I let the advertising wimp play kneesies all through lunch.