A slang used by Hippies
since the mid-60's to denote the corruption of the US, particularly in the empyreal business and corporate sectors, most specifically global chains, such as McDonalds, Starbucks, and Wal-Mart. "An empire of selfish pigs" somehow got shortened to "Pig empire". Sometimes also used to refer to the American government
Dude 1: Where you going for lunch?
Dude 2: McDonalds.
Dude 1: Bleh, Why don't you go to a local sandwich shop, I don't want to support the pig empire.