The act of taking someone's backback, removing its contents, turning the aforementioned backpack inside out, replacing the contents, and zipping it shut.
"Dude, Johnny just left his backback unatended. Let's Punknasty that shit!"
"Haha, you just got punknastied, fool!"
"Haha, you just got punknastied, fool!"
by Maximus Lloyd November 04, 2007