Some worthless, pathetic excuse for a person decided he needed gas more than I do, so he pumped it out of my truck in the middle of the night. He was even nice enough to throw the cap in the street so it could get run over and leave the gas door open so the pouring rain could find it's way into my tank. So, I'll make it easier for him next time and just leave a full can of fuel in the back. The question is, what kind of fuel should the can be full of? What is the worst possible thing someone might accidently pour into their gas tank? I'm thinking methanol which should destroy most of the rubber/plastic parts in the fuel system. Is there something worse I could use?