I don't think the regime in Pretoria is that nuts. However, if the Samora Machel government in Mozambqiue takes its sabre rattling to another level, and actually invades South Africa, I could see a SA nuke being dropped on Maputo and Beira. That would destroy all sympathy for SA in the rest of the world though.
I don't know if you guys heard, the Campaign for Nuclear Disarmament now has a South African chapter. There were protests outside parliament last week, and members of the SA CND blockaded the main road into Pelindaba, SA's main nuclear research facility.