A blast from my past.
As a teenager, living just outside Ft. Bliss while Dad was in Vietnam, we kids would hike up to the "VC Village" on the slopes of Mt. Franklin. There was tons of stuff like smoke grenades, artillery simulators, 7.62x51 and 5.56 ammo just laying around, as well as discarded magazines. Since I was issued an M14 in HS ROTC, I made sure to have a couple of those mags loaded up with ammo at home, just in case of a "Red Dawn" situation.
We would set off smoke grenades and artillery simulators, sometimes shoot them with our .22's, and when we saw the MP's coming up the hill in a Jeep we would hide out in the tunnels in the fake "VC Village". They never found us, would get tired, and drive back down the hill leaving us to our mischief. (I think that the statute of limitations has expired for our transgressions.)