The act of emptying someones backpack, then turning it inside out, putting everything back in and zipping it up from the inside. Some even go as far as zip-tying the zippers together to make it extra aggravating. Also possible on some backpacks is a supernug, when you flip a backpack inside out and stuff it all into the small front compartment. This is really a dick move.
"What the hell is he doing? Oh, he's just nugging that poor kid.