Common definition: Yeshua casts the group of demons out of the possessed man into a herd of swine; i.e., group of pigs.
Underground definition: Since the Jews didn't raise pigs, the herd of swine was the Roman authorities; the police.
Carl: I'm going to go rob a bank.
George: That's a good way to attract a Herd of Swine. Congratulations you idiot...