The Truckie above is right about CHEP pallets. These blue pallets with white lettering are ubiquitous in Australia, and there are a number of yards at which you can pick them up and drop them off.
Because it's a rental thing and pallets aren't free to manufacture, there's a penalty if you don't bring them back. AND -- amazingly -- it is at least sometimes NOT on the people who picked them up, or loaded or unloaded them, but on the person who authorised the job with the contractor, who may not have ever even SEEN the pallets in question.
Why would this happen? Because anyone can rock up to a CHEP yard with a bunch of blue pallets and receive back, in cash, the deposit for said pallets. Going pallet-hunting is apparently not an uncommon activity among Australian tradesman after a big night of drinking when the next payday is still days away. Most of us would have no reason to know this, and presumably the economy somewhat relies on this, but basically an unguarded CHEP pallet is like a $100 note (or whatever the deposit is... as I recall, it isn't a small number) sitting on the ground.
So, a friend of mine, in charge of maintenance for a piece of public infrastructure, one day had some maintenance done. The supplies for this apparently came on CHEP pallets. He knows this not because he'd ever been TOLD about any CHEP pallets by the workers... but because one day CHEP sent him a bill for $4,000. He wrote back, don't know anything about your pallets, never seen 'em, don't have 'em, not paying this invoice. SOMEHOW this degenerated into a personal attack by CHEP on him, calling him at home, nagging him for these pallets he'd had nothing to do with. It went on for months. His management backed him on not paying the invoice, but that didn't help in the context of CHEP taking the dispute personal.
One day he got sick and tired of this, and called up the contractors in the middle of the night. "Round up your mates, and round up a big-ass truck. We're going for a drive." And they drove around all night, picking up any blue pallet that wasn't nailed down. Final count it was something like hundreds of them, if I recall correctly. They dropped them off at CHEP. He used the funds to pay the CHEP invoice and pocketed the rest and told the contractors they better not ever say another word about this.
Apparently in recent years, CHEP has begun to bar code pallets so they can track them, so I have no idea if they're still easy, untraceable currency as they were 5+ years ago.