When I was in the Marines it was used as a greeting, a derogatory term, a compliment, and a chant of unison. It came from the China Marines in the 30s.

As a greeting: "Semper Fi Mac," the first Marine says, "Gung Ho" said the second Marine. (The literality of this is "Always Faithful Brother" and "Working together.")

Derogatory: "That Gung Ho SOB is gonna get us all killed if he doesn't slow down."

Complimentary: "He's one Gung Ho SOB isn't he!"

Chant: Most often while running as a form of cadence.

"I don't know but I've been told"

repeat by platoon

       "Gung Ho Marines are mighty bold"

repeat by platoon

       "Gung Ho"

repeat by platoon

       "Gung Ho"

repeat by platoon.

I was told by the China Marines I met during my time in the military that it was Chinese and literally meant "Working together."

Steve