They aren't just a side to go with your burger or your nuggets, they're a lot more than that.
They can be a sole hangover cure or even a delicious meal by themselves that you can randomly crave - and now we know why.
On the companies website, the flavour is listed as containing "hydrolysed wheat and hydrolysed milk as starting ingredients.” which combine to make a "natural beef flavour".
This process creates a meaty taste within the fries, something that makes them different from other fries that are out there.
If you want to learn more about the wondrous fries, or just are a McDonald's enthusiast, here's a video of the whole process.