Green’s Dictionary of Slang

(S.Afr.) an outdoor privy.

1966		C. Van Heyningen Uys Krige 94: They chatter to Luis about the house they have built [...] a house that even has a ‘kleinhuisie’.
1978		Sun. Times (Jo’burg) 14 May 6: The second cobra to call on an occupied ‘Kleinhuisie’ (outside lavatory) in Anysberg [...] this week was routed by shouts of a housewife [DSAE].
1988		S. Gordon Under the Harrow 175: At the back was a cabbage patch and the kleinhuisie (Little house), the euphemism for the long-drop lavatory.