This is supposedly a true story from a recent Defence Science Lectures
Series, as related by the head of the Australian DSTOs Land
Operations/Simulation division.

Theyve 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
helicopters 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 theyve 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…