you must stay on the plane

Example Skiplagged listings for flights that don't end in Chicago, but go through Chicago.  As part of its settlement with Orbitz, Skiplagged will no longer direct people to purchase their hidden city fares through the travel-booking site.

United Airlines, Orbitz Ask Court To Stop Site From Selling “Hidden City” Tickets

I live in Philadelphia and if I want to visit a friend in Chicago for a weekend, it will cost me several hundred dollars for a round-trip ticket on U.S. Airways. For significantly less money, I could book what’s known as a “hidden city” ticket from Philadelphia to Orlando via Chicago, and then just get off the plane when it stops in Chicago. Most airlines ban the practice, but there’s not much they can do to stop it. They can, however, sue to stop a website from promoting and booking these verboten fares. [More]