When the Oklahoma Territory was to be opened to everybody people from all over the country flocked to the area for free land. All were supposed to rush into the territory at the boom of a cannon. Those who left early were called Sooners, and those who left on time Boomers. Thats where it is from in a very short summary.
http://www.tigerforums.com/showthread.php?s=&threadid=10639&highlight=boomer+sooner Can we make this a sticky??
