A wolf and a jackal often hunted together. Once, they came across a sheepfold with walls that were too high and sturdy for either to climb alone. They devised a plan: the wolf, with its long forelegs and short hindlegs, stood on the shoulders of the jackal, who had short forelegs and long hindlegs. By standing on its hind legs, the jackal lifted the wolf high enough to scale the wall and reach the sheep.
This idiom describes the act of collaborating with others to do evil.