It’s all good. 
Am I the only one, then, who thought it stood for O. Keedokie?
<slinks away>
I was taught in some creative writing classes to always use, “okay.”
Not sure why. I just took it at face value and have done it that way since. Okay?
[QUOTE=poll]
How do you spell … you know.
[/QUOTE]
I spell it “you know”.
And to answer the question, AP Style says “OK” so that’s always been OK for me.