No, it's not a disco ball thing, it's meant to keep away sea gulls. The idea seems to be that their new thick-cut fries are so good that those fry-stealing birds will even be more likely to snatch them right out of the box. To deter the flying potato-thieves, the burger chain came up with fry boxes that are printed on shiny holographic paper that is supposed to confuse and ward off sea gulls due to the way that light reflects off of it (apparently, according to National Geographic, it should work). The concept draws inspiration from the "scare tape" that some farmers use to protect their crops from birds.
They're calling the fry containers "The Pack That Scares Gulls" and besides the chrome holographic surface, the boxes contain exclamations such as "Scram!" and "Shoo!"
Given that sea gulls are more commonly found near the beach (although living 25 miles inland, I saw plenty of gulls back when I was in school), the limited edition containers are only available in eight coastal Hungry Jack locations including Bondi Beach, Surfers Paradise, and Seaford.
Here's the video they put out explaining the concept:
Image via Hungry Jack's.