Green’s Dictionary of Slang

1. (S.Afr.) one kilometre.

1983		Sun. Times (Jo’burg) 13 Mar. (Mag. Sect.) 3: We can’t even shorten the kilometre properly. The abbreviation is supposed to be km, in which case where do the young, in particular, get the expression: ‘I was only doing 90 kays, man’? [DSAE].
1986		P. Slabolepszy ‘Boo to the Moon’ in Mooi Street (1994) 116: No mosquitoes for a ten kay radius.
1990		P. Hotz Muzukuru 41: We took the terr to the nearest cop shop, about 40 kays to the south.
1992		P. Slabolepszy ‘Return of Elvis’ Mooi Street (1994) 307: Why? Why get in the car – drive over two hundred kays.

2. see K n. (3a)