A kind of chili at Skyline, a chili chain in Ohio, Kentucky, Indiana, Michigan, and Florida.
They also have a 3-way and a 5-way.
A 4-way chili is spaghetti topped with Skyline chili, cheese, and diced onions or red beans. In other words it's a 3-way chili with onions or beans.
I'm here at college from IN. You can imagine the amusement and confusion that went down when I heard about the "famous 3-way".