It's a stupid question but for some reason I really want to know this.

Whenever I see someone spell it any shortened way, it makes me physically cringe despite the fact that they're all technically correct.
Interesting question.

I sometimes spell it "okay" as well, but seeing as it probably originates from 'orl korrect', I think OK somehow makes more sense.

Okay that's it :D

I use both ok and okay. Depends on what I'm typing really :P

^Same here!

I usually type oki :D
really don`t know why