In the summer of 2004 I was enjoying the mountainous view and ample sun of Kandahar, Afghanistan. It was there, eating one of my allotted MREs, that I noticed the MRE heater was printed in large letters "Do not expose to flame." Being a bored jarhead, I couldn't help but try and figure out why. Being able to rub a few brain cells together, I thought about how the heaters are activated by the addition of water. Since water is hydrogen and oxygen, I was willing to bet that those were some of the reaction products. I never bothered to look it up, but I did find that whatever was coming out with the steam was also quite flammable.<p>Once that was proven, I recalled that recently a contractor had dug a well near our work site. I ambled over and found a 3 foot long, ~3 inch diameter steel pipe that had a 90 degree elbow with a quick release cap.
All that was required after that was a touch hole, added with a drill, some MRE heaters, and projectiles.<p>Potatoes were not available there, but fruit like oranges and pears were. I started with an orange and just jammed it into the very end of the barrel, it was too big to go all the way in, and went for it. The distance was laughable, 1 or 2 feet, but the sound? Everyone came running out of the work center tents because they thought I had just loosed a round from my weapon.<p>After being called an idiot by the local Lieutenant, I switch to only pears, which were easy to jam in hard enough to cut the excess off.
At this point, I was lobbing pears across the perimeter road, into the scrub / minefield outside the wire. Never found a mine with it though.<p>All my fun ended one faithful day when I accidentally dropped a pear in front of a Romanian MP truck on patrol around the perimeter. The 50 cal on top turned to point at me, I dropped the pear cannon and walked away, never to return.