A utterance, with widespread use in the U.S. military, made famous by Al Pacino in "Scent of a Woman". This is all well and good, but for the fact that he mispronounced it.1
You see, "hoo-ah" is pronounced "hoo-ah!" (emphasis on the second syllable), rather than "hoo!-ah" (emphasis on the first), which is how our friend Al deemed fit to pronounce it. More's the pity...
1 This is, of course, an opinion.
etoile says re Hooah: I disagree with your statement that the stress is on the second syllable in "hoo-ah" - I work for the DoD and there are military members all over my building, and I've always heard them pronounce it HOO-ah. (sometimes they stress the ah too, more than Al Pacino did, but the HOO is still dominant.) just my thoughts.