What does o.O mean when posting online?

[stilldeveloping]

I am familiar with a good number of abbreviations used when texting, as well as the basic emoticons. However, this confuses me. I saw it 3 times when reading Facebook comments tonight!!! So what does o.O mean???

[Ground]

That's just like raising your eyebrow, i think.

[Chris G]

It's a bug-eyed look of surprise.  I suppose you could call it a wtf smiley. 
 
 

[Daniel]

its Some Kind Of Look It Could Be a Surprised Look Or a Wink i Could be Wrong Ask The Person Who is Using it

[Angeleyes]

It like a confused look, or a wtf, what the heck or a woah sort of thing.