The "Never fired, only dropped once" joke started with the South Vietnamese. U.S. soldiers in Vietnam made the joke up about the ARVNs. Just from what I have read in books, ARVN soldiers were very poorly trained, full of VC and NVA spies, unmotivated, forced into service, and very very scared. So its kind of a grim joke. Yank some kid off the street, hand him a rifle, throw him into the meat grinder. As far as I know, there was no 'tour of duty' for ARVN soldiers. I believe it was 'fight till ya die'.