One of America's best-loved writers of short stories was William Sydney Porter -- better known as O.Henry.

VOA: special.2010.12.17

It was a short way of writing a different spelling of the words all correct. Some foreign-born people wrote all correct as o-l-l k-o-r-r-e-c-t, and used the letters O.K.

VOA: special.2010.02.28