Depending on if there are caps, or where they are/how arranged, here we go on text exotes:
1.)
o.o : blank stare, as in "You've just lost me" Or "I care about this...Why, again?"
2.)
O.o ; o.O : Confusion, usually used together.
3.)
O.O : Suprise, shock.
1.)
Person: (insert technical jargon here)
Me: o.o
2.)
Person: and because of this, such evented happened, at such time, for such reason.
Person: You get it now?
Me: O.o
Me: o.O
Me: That was supposed to be helpful?
3.)
Person: (I'm blank on ideas, but anything that would suprise me)
Me: O.O
Me: Really?!
1. Similar to the emoticon o_o but with an extra underscore (_).
Upper case Os are used more often to denote more shock than lower case Os.
Generally used in the same fashion (shock, look of bewilderment, blank stare, skepticism, or weirded out). However, the extra underscore is added to denote more stronger emotions.
2. Also may be used when an o_o may not want to be repeated.