V; At almost any concert (though mostly Metal concerts), people Crowd surf. Crowd-Jacking is the act of moving towards a crowd surfer heading in your direction and reaching into his pockets, stealing his Cell Phone, Wallet, Cigarettes, Knife, Money, Etc. in the chaos as he passes over your head and the heads of all the other moshers in the pit. In the fun, the Crowd surfer usually never even notices he's just been jacked.
"I don't go to see The Casualties play live anymore because people are always Crowd-Jacking there and ruining the fun."