I also looked this up, and found the original paper that coined the term, which starts:

> The "Wolf Fence" method of debugging time-sharing programs in higher languages evolved from the "Lions in South Africa" method that I have taught since the vacuum-tube machine language days. It is a quickly converging iteration that serves to catch run-time errors.

http://dl.acm.org/citation.cfm?id=358695 (if you have access)

Anyone know what the "Lions in South Africa" method is? I couldn't find it via Google, it just kept turning up references to the same paper.