We recently warned about pulling into a gas station and subsequently getting in and out of your car while refueling. It creates static electricity that could cause a spark and a serious fire unless you're ?discharged? by touching metal before reaching for the gas nozzle. Now another static electricity danger has surfaced -- filling up a gas can while it's in the back of a pick-up truck -- especially one with a plastic bed liner. The problem is that the liner acts as an insulator, preventing static electricity from being discharged to the truck body. It accumulates in one of two ways: from friction created by sliding around while you drive or by gas flowing through the hose and falling into the can. The danger is equally serious for plastic and metal gas cans. This warning extends to the trunks of autos as well, since carpeting is an insulator, too. The simple solution? Always remove gas cans from vehicles and place them on the ground before filling them.