Exclamation for when "OMG" is just not enough to express the surprise of the the moment.
Person 1: I just found a wall charger that works with my iPad!
Person 2: O-M-SQUEE!!!
The HOTTEST videogame character from Nintendo's, Legend of Zelda videogame series.
Girl 1: O. M. G. LINK IS THE HOTTEST GUY EVER! *squee*
Girl 2: I KNOW!! HE IS LIKE, SO HOT! :D