o__o 

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.

1. Person 1: I found out I was adopted
Person 2: o_o

2. Person 1: And that I'm really a robot
Person 2: o__o

Person 1: It all came to me when I fell off a cliff and into a girl's house
Person2: O__O

o__o by Guest3 June 18, 2011

o__o 

o__o is the shape of the Google Pixel 3XL's layout inside the massive runway of a notch.

Did you see Google's o__o? You could land a plane on it!

o__o by Axle182 October 16, 2018

o.o; 

The ; is represented as a sweat drop.

See o.o

P1: OMG WOW HOW ARE U?!

P2: o.o;

o.o; by Wistful July 6, 2005

o_O 

Confused, stunned, or weirded out.

o_O what do you mean?
o_O what is that?!
o_O Whoa wtf

o_O by DWBoy February 19, 2003

o////o 

An emoticon used to indicate the person is blushing, embarassed, etc.

person 1: zomg, do you really like him?!
person 2: um.. o////o

o////o by dfskdshjdsahdsa April 28, 2006

O_O!

Very shocked

You slept with a dog?! O_O!

O_O! by Leo =] April 14, 2003

o.o` 

an emoticon used generally to express confusion. The accent at the top is not a sweat drop, but rather a raised eyebrow.

AKA: o_o` o.O

peep1: So I says to him, I says "dude" and he was like "check it, man"...you know what I mean?

peep2: ...o.o`

o.o` by St0DaD May 4, 2007