The prank was a kick by a trucker to the back of the knees of a co-worker while they waited all day for a ship to arrive at the docks. The blow caused the co-worker to collapse, resulting in serious back injuries from which he never recovered.
The trial judge and the majority of the Victoria Court of Appeal concluded that there was an insufficient connection between the wrongful act and the course of the trucker’s employment or conduct authorised by the employer: Blake v JR Perry Nominees Pty Ltd,  VSCA 122. The theory that the kick was the result of work-induced boredom and frustration was rejected. Neave JA, in a strong dissent, thought otherwise. There was evidence that the employer had not instructed the truckers to refrain from playing football or cricket while waiting for the ship to arrive, or from engaging in the horseplay that was typical among them. It was therefore predictable that they would get bored during a long wait on the dockside and that horseplay would ensue – to the point where any resulting injury was incidental to acts authorised by the employer. Good review by the majority and dissenter of leading Australian, English and Canadian authority.
[Link available here].