The following power supply circuit is a high voltage power supply. It is a very useful source which can be effectively used in many applications like biasing of gas-discharge tubes and radiation detectors etc. Such a power supply could also be used for protection of property by electric charging of fences.
The current requirement of power supply is of the order of a few microamps. In such an application, high voltage would essentially exist between a ‘live’ wire and ground. When this ‘live’ wire is touched, the discharge occurs via body resistance and it gives a non-lethal but deterrent shock to an intruder.

Source: http://www.electronicsforu.com/efylinux/circuit/cir96.htm