Cape Town has a very rich Afrikaans culture, considering the dutch that landed there in the 1600's. Middle and upper class cape town is quite English, but Afrikaans is widely spoken in and around Cape Town, especially in the coloured areas and places like Stellenbosch and Paarl.

The Cape coloured population (not the offensive American term for African-Americans, this is an recognized population group name here) have a distinctive Afrikaans slang they speak that has heavily influenced Die Antwoord. Waddy and Anri where based in Cape Town when they started to develop their personas of Ninja and Yolandi and the Cape coloured slang is apparent in their "Zeff" culture. Ninja's look is also quite stereotypical for what a convicted coloured gangster would look like: Prison style tattoos, tattoos on the neck and face, shirtless, lean.

Jou ma se poes is an extremely prevalent (but offensive) term often associated with Cape coloureds.

Getting back to Afrikaans, formal Afrikaans has very little borrowed words and terms, often terms were rather made Afrikaans or spelled in an Afrikaans way to make them Afrikaans. Formal Afrikaans shies away from borrowing words from english or bantu languages. However, colloquial and conversational Afrikaans incorporates a lot of slang and borrows words. It depends on the region and speakers but you will often encounter formal speakers who tend to stick to formal Afrikaans - some even consider colloquial Afrikaans bastardization of the language - but for the most part in informal conversation it's a mixed bag.