This is supposedly a true story from a recent Defence Science Lectures Series, as related by the head of the Australian DSTO's Land Operations/Simulation division.
They've been working on some really nifty virtual reality simulators, the case in point being to incorporate Armed Reconnaissance Helicopters into exercises (from the data fusion point of view). Most of the people they employ on this sort of thing are ex- (or future) computer game programmers.
Anyway, as part of the reality parameters, they include things like trees and animals. For the Australian simulation they included kangaroos. In particular, they had to model kangaroo movements and reactions to helicopters (since hordes of disturbed kangaroos might well give away a helicopter's position).
Being good programmers, they just stole some code (which was originally used to model infantry detachments reactions under the same stimuli), and changed the mapped icon, the speed parameters, etc. The first time they've gone to demonstrate this to some visiting Americans, the hotshot pilots have decided to get "down and dirty" with the virtual kangaroos.
So, they buzz them, and watch them scatter. The visiting Americans nod appreciatively... then gape as the kangaroos duck around a hill, and launch about two dozen Stinger missiles at the hapless helicopter.
Programmers look rather embarrassed at forgetting to remove *that* part of the infantry coding... and Americans leave muttering comments about not wanting to mess with the Aussie wildlife...
As an addendum, simulator pilots from that point onwards avoided kangaroos like the plague, just like they were meant to do in the first place...