Southern Colombia, 1992 and 1993. With the Air Force (if you can believe that). Can't really say much, but I will say that all the talk in the world doesn't mean anything once the bullets start flying. You really see who you do and don't want in your bunker/foxhole right away.
Never killed anyone though... didn't even fire at anyone. It was still perhaps one of the greatest moments of clarity I've ever had.
MiniD