Gung-ho is a Chinese phrase usually translated as "pull together" or "strive for harmony". It was used in the WW2-era Chinese Communist Party's 8th Route Army, led by Chu Teh.

The phrase entered the American vernacular when it was picked up by then-Major Evans F. Carlson, USMC, in his travels with the 8th. He then used it during his (unconventional) command of the 2nd Marine Raider Battalion. From there it spread throughout the Marine Corps (hence the association between the two) and into American society as a whole. It is now frequently used as an adjective meaning enthusiastic.