A fork of Rural Dictionary
A "Manchester" is the act of calling a friend or acquaintance on a statement they made. When a person states definitively that they will perform an action, anyone within earshot can call "Manchester!" After the call, the callee must either perform the act or receive a swift punch in the stomach. Originated at Rose-Hulman Institute of Technology on BSB 1 in 2008-2009.
Andy: "I'm going to go do jumping jacks naked on the frozen lake!" Tim: "MANCHESTER." (At this point, Andy either does jumping jacks naked on a frozen lake, or gets punched.)