The next time you pull your car up to the pump at a gas station, it could pay to read the instructions sticker affixed it. The instructions are easy to ignore, however, they are important. Along with telling you not to “top off” your car, they also say to touch a piece of metal before pumping gas. But why?

Touching metal can prevent a disaster

Have you ever rubbed your feet on the carpet to build up static electricity so that you could shock your friends? We’re sure you have, at least once. And it’s that type of electricity that can cause problems at the pump.

Apparently, sliding out of the seats of your car to pump gas into it can lead to a build-up of static electricity within you. And if you don’t ground yourself by touching something metal first, it can cause the gas coming out of the pump to ignite, which could lead to much greater consequences.

“You get that static discharge from your body to that metallic nozzle, and when that occurs, there’s potential for a spark to happen,” says Scott Boorse, director of technical programs and industry affairs for the Petroleum Equipment Institute told Reader’s Digest. “That spark is enough to ignite any of the vapors that are around the tip of the nozzle.”

If you would like a visual representation of this occurrence, watch the following video below:

How can you prevent static electricity from igniting the fuel?

Luckily, there’s an easy solution to preventing static electricity from igniting the fuel from the pump. All you need to do is simply touch something metal with your bare hand before touching the pump. For example, you can touch the door of your car or even the metal strips that run alongside the gas pump.

Either way, by doing this you will ground yourself and dispel any static charge that you might have. Also, do your best not to get back into the car while you’re pumping gas as that can lead to you getting a static charge all over again. But even if that happens, you can touch something metal and not have to worry.

If the fuel does ignite, here what you should do

It probably goes without saying that you should always turn your car off before you pump gas and refrain from smoking while doing so. If a flash fire does occur, leave the nozzle in the car and back away from it.

Shut the fuel off at the pump using the red “emergency stop” button or lever on the gas pump itself. After shutting the pump, notify the gas station attendee so that they can shut off all of the pumps with the master switch.

If you were to pull the pump out of the vehicle during a flash fire, it’s possible that the flames will ignite the stream of gasoline and cause the pump to act as a flame thrower and cause more damage to your surroundings, yourself, or others. Since there is not enough oxygen in the gas tank to cause an explosion, it’s better to leave the pump in the car until the attendant can shut off the fuel.