'oo' pronounced: like in the words: too, new, noob, etc.
can be put in to any sentence or phrase in different moods or describing your emotion toward something or someone. basicly 'oo' can be use if your happy, suprized or confused, sad, or if you simpily got hit in the back of your head (or when you get hit by someone or something)
happy - oo (^^)
suprized - oo? (huh?)
sad - oo... (;-;)
hurt - oo!! (ouch!!)