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.