One time I brought peanut butter in my luggage. It looks like plastic explosive on the scanner so they have to open it and test it. Our teacher actually advocated that we bring it and those 36 packs of AA batteries because they look like plastic explosives and bullets, respectively. He really liked to mess with the TSA.
This was post 9-11, I don't know how we didn't all get arrested.
This was post 9-11, I don't know how we didn't all get arrested.