Excite News:
Soldier 1: How you doing?
Soldier 2: Fine. How you doing?
Soldier 1: Hooah.
For the different branches of the military, each vastly competitive with and jealous of its distinctions from one another, hooah has become something of a sore point. Marines and sailors have their own saying, more of a 'hoo-RAH' or a 'hoo-yah,' which they claim is entirely separate in origin.
The Air Force brass once reportedly got so irked about sharing 'hooah' with the Army that it tried to get airmen to shout 'Air power!' instead. But 'Air power!' did not have the same potency as 'hooah,' and has been largely abandoned.
...
Yet the use of hooah by the uninitiated is generally frowned on. Carter recounted that a drill sergeant barred him and his fellow recruits from saying hooah until they had finished the basic course and earned the right.
And civilians uttering hooah are generally looked upon with either disdain or the astonishment of a person who has just heard a koala bear recite lines from e.e. cummings."