An emoticon of one yelling. The > < represent the closed tight eyes, generally, the o being the mouth. >o< and >O<, with differing capitilization of the o, represents different volumes of yelling.
In addition to adding energy to a sentence, it can be used to represent sarcastic overenthusiasm.
coolj: You guys shut up for a minute and think >O<
bobbyk: I just got a new bike
ffingerlick: thats amazing i am horny because of that news >o<