What does Backpack Flipping mean?

Backpack Flipping meaning in Urban Dictionary

The art of having ones backpack flipped inside-out. In despite the popular term "Nuggeting". When a backpack is flipped where is the nugget. I seemed all-over for this and I also could not find it everywhere. I searched within the backpack and I searched outside. I became actually searching for a nugget cause I became pretty hungry at that time.