The story
Onomatopoeic. Foreigners who came to the townships could not speak the local languages. One theory on the origin of this term is that their own languages sounded like kwirikwirikwiri to the locals. A more plausible theory is that this term was a corruption of the word "korekore". The Korekore are a sub-group of the Shona people in neighboring Zimbabwe.
Etymology from Wiktionary, CC BY-SA 4.0.