On exchange with a foreign Air Force, I was about to go on exercise and picked up my lunch box before adding a Mars Bar from the Squadron Crewroom Shop. I also bought a few extra Mars Bars which I shoved into my Bergen. During our lunch stop I and my colleagues tucked into our rat boxes. One saw the Mars Bar in my box and said "Hey, how come you got a Mars Bar and we didn't?" I didn't say anything but opened my Bergen and handed him one. On seeing the stash of several Mars Bars he then berated me for taking them out of other people's boxes. Still I didn't respond. Half an hour later, after he had spoken to the rest of the detachment, he realised that there hadn't ever been any Mars Bars in the lunch boxes and humbly proferred his apologies! He didn't hear the end of it for the rest of the det.....and most it came from his own colleagues!