Hooah

Hooah /ˈhuːɑː/ is military slang Originally HOOA used by US Army Airborne in World War II meaning " Head Out Of Ass " and was a spin off of Radio Operators HUA "Heard Understood Acknowledged" as the term spread throughout the Army it became more of a general meaning "anything and everything except 'no'".

Used by soldiers in the U.S. Army, which accounts for the vast majority of the usage of the word.

Some popular usages of hooah include:

HOORA used by US Army Rangers

...
Wikipedia