Originally Posted by
GPMG
being referred to as a Grunt.
. Slang An infantryman in the U.S. military, especially in the Vietnam War:
"They were called grunts....They were the infantrymen, the foot soldiers of the war" Bernard Edelman
I understood it was a US acronym like GI - Government Issue or
Government Reject Unfit Normal Training.
Definitely not one of HM's Jollies.