Oh.. we use the same word, but spelt differently.
Kak or Kuk. I prefer spelling it this way, makes the word sound much strong since you emphasise on the K sound.
You guys have probably seen me use that word already.
I swear... South Africa slang is practically the same as UK/Aussie slang, except with different spelling and pronounced slightly differently.
Kuk is slang for penis in Norwegian.