When smoking and passing around marijuana in a circle, if one takes a hit and keeps the smoke inhaled until one receives the marijuana again, this act is known as a one hit Chicago. There is no significance with regard to referencing the city of Chicago. The actual term originates from Philadelphia, PA. There is also a closely related "smoking game" by the same name.
John likes to one hit Chicago at parties or when he has sour deez. His high record for one hitting Chicago is nine people in the group. He almost one hit Chicagoed with a group of eleven people, but someone made him laugh before the guy next to him could take a hit.