The original owner, John Montgomery, liked the sound of the O.K. (which, during the mid-1800s was a time of "pun playing in the newspapers" and "pet names" and thu…s, OK meant "Old Kinderhook.".
ADDED INFO: This famous gunfight that took place in Tombstone, Arizona on October 26, 1881 did NOT take place at the OK Corral, but a vacant lot on Freemont Street in the alley by "Fly's Photo Shop.".
I came across a good website you may want to visit: www.tombstone1880.com/archives/wyatt.htm.