I recently went to New Zealand. Since it is an outdoorsy type of place I put my camelback water bladder/backpack in my big duffle bag and had a great time. Since I'm a responsible hiker, I have a standard emergency kit in my backpack that contains things like a compass, foil space blanket, ace bandage, banana powerbars (these are so gross I'll only eat them in an emergency), etc.
Cut to me going on a hike last Monday and grab my trusty back with the kit already put together. I wanted to put something in my emergency pack and noticed a slip of paper from the TSA informing me that they had confiscated my pack of 25 windproof matches. If I had a scanner I would post an image of the notice. The rule apparently is that knives must go in your checked baggage and matches must be in your carryon baggage. Don't ask me to explain this. Also don't ask me to explain why I can't use my PocketPC to read books during takeoff and landing. These things cannot be explained.
So, imagine that I had gotten lost in the mountains last Monday and it started to get cold. Normal people would have dispaired and rolled over and died. But not me! I was a boy scout and was prepared ("Be prepared, its the motto of the Boy Scouts!"). I'd reach in to my emergency kit to get my matches to start a fire. Instead of finding life saving matches I would instead find a very official looking notice from the TSA letting me know that I'm screwed.