Green’s Dictionary of Slang

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

1944		E. Wilson 15 Sept. [synd. col.] I was able to play a little kneesy with three of the greatest stars of stage and screen.
1958		T. Capote Breakfast at Tiffany’s 58: I let him play kneesie under the table.
1965		K. Marlowe Mr Madam (1967) 168: When we sat next to each other we’d play kneesies.
1972		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.
1976		H. Selby Jr Demon (1979) 54: They [...] played a little kneesies and pinch assie under the table.
1982		Hanson & Muchmore Coming Out Right 31: Don’t grope anybody, rub thighs, hold hands, play footsy or kneesies.
1999		J. Kaye Stars Screaming 285: She was there, on the deck, drinking rum drinks and playing kneesies with that old man.
2003		A. Marston Yesterday’s Spring 79: That luscious blonde sitting ringside and playing kneesies with her pretty boy escort.
2021		J. Ellroy Widespread Panic 75: I sat close to Stretch. We played kneesies.

2. in fig. use.

1991

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