I remember one campout in particular, it was a nice enough weekend weather wise, but a Scout learned a hard lesson.
The Scouts started unloading the cars and sitting up camp. After a while one of the older Scouts started hunting around camp trying to find his backpack. Turns out he told his brother to put it into the car before they left home. Well he didn't. Luckily their dad was on the outing with us and told his son, well guess your going with out your backpack then. A discussion followed as you would guess, the Scout complaining he has no sleeping bag, jacket, flashlight, mess gear, etc. The father said, well thats to bad this will teach you responsibility, and so. The father did give his son an extra sleeping bag which he planned to have as extra padding under his bed. The Scout made it through the campout with out any major problems other then having to bag and barrow everything. As I recall he was on KP a lot (common trade for loan of a plate, etc). Needless to say the Scout never had that problem again … he always had his gear and it was always properly packed.
Notes: this was in a moderate climate, it was not overly cold, etc. Also it was a car campout and there was enough gear to be shared. We as leaders know what was going on and knew the Scout was experienced enough to handle the unpleasant situation. I will also not the dad was experienced in the outdoors as well, and later became the local Scout Camp's Camp Ranger.
Lesson: don't rely on someone else to do what you should do yourself