9. Bear Spray

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In a way, you can almost understand someone lugging one of those super-size blaster cans of pepper spray bear repellent around, especially considering that it was found in the carry-on bag of a traveler in Anchorage, Alaska. While bear spray might be a perfectly reasonable item to carry around the wilderness areas of Alaska, attempting to bring it on an aircraft full of people is not terribly bright. Beyond the notion that it could be used as  a weapon, there is the possibility of something like that malfunctioning and filling the aircraft with pepper spray, which could have extremely serious consequences, especially for people with respiratory problems.