Kangaroos with missiles, or Reusing code for fun and profit...but mostly fun.

Ah, the killer kangaroo story. Maybe you've heard of it, maybe you haven't. As the story goes, work was being done by the Australian Defense Science and Technology Organization's Land Operations/Simulations on a simulator for helicopter pilot training. It included, among other things, herds of kangaroos, since startled animals could give away a helicopter's position. “Being efficient programmers, they just re-appropriated some code originally used to model infantry detachments reactions under the same stimuli, changed the mapped icon from a soldier to a kangaroo, and increased the figures' speed of movement.

“Eager to demonstrate their flying skills for some visiting American pilots, the hotshot Aussies "buzzed" the virtual kangaroos in low flight during a simulation. The kangaroos scattered, as predicted, and the Americans nodded appreciatively . . . and then did a double-take as the kangaroos reappeared from behind a hill and launched a barrage of stinger missiles at the hapless helicopter.”

It makes a good story, and shows quite nicely that even when reusing code you have to be careful, but as it turns out, there's a bit more to the story, and it wasn't a mistake so much as a bit of fun. The kangaroos weren't there out of necessity, the interesting bug was discovered rather early, and the “kangaroos” were firing beach balls, the default weapon of the simulation code.

Initial story found somewhere on the net, the rest from the snopes article here