Elon Musk has been selling flamethrowers. Which begs the question: What use could your average American possibly have for one?

A flamethrower is a weapon that operates much like a squirt gun, but instead of water it spews flammable liquid that's ignited as it exits the barrel.

Musk announced on Twitter on Sunday that his The Boring Company was selling flamethrowers for $500 to raise money for his tunnel drilling project. The CEO who's known for companies like Tesla (TSLA)and SpaceX told his followers on Thursday that the company had sold out.

Now that a slew of Musk fans will potentially be running around with flamethrowers, CNNMoney reached out to the makers of two popular models, Throwflame and Terra Torch, to find out how to use them.

Here are five good uses for a flamethrower:

War

World War I marked the debut of the modern flamethrower when soldiers used them in trench warfare. The weapon also figured prominently in World War II. The U.S. Marines used them to deadly effect against Japanese bunkers in the jungles of the Pacific islands. But they were hazardous for the user as well as a target for enemies. The U.S. military hasn't used them in combat since the Vietnam War.

Dan Jones, owner of GelFire Systems in Oregon, said the Army uses his Terra Torch incendiary device, but not for combat. He said it's to burn brush to clear firing ranges and ferret out any "hot mortars" that might be lying in the grass.

Related: Flamethrowers, once used in war, are now sold to civilians

Firefighting

It might seem strange, fighting wildfires with fire, but that's exactly how they do it. Jones counts among his clients the Kern County Fire Department of California. The Terra Torch is a handheld flamethrower than can spray more than 50 feet, and is connected by a fuel line to a 50-gallon tank that's mounted in a truck or off-road vehicle. He calls it a "glorified, modified spray gun designed to handle gelled gasoline."

He said firefighters use it for controlled burns, where they stop a fire from spreading by burning everything around it. "They call it backburning," he said. "You get ahead of [the wildfire] and lay a fire line behind it. Basically you are controlling the excessive fuels."

Land management

Jones has also sold Terra Torches to the Interior Department, the Forest Service, the Fish and Wildlife Service and any rancher who can afford the $20,000 price. He said farmers will use them to clear land for crops, and the government uses them to burn out overgrowth to create habitats for animals or to prevent uncontrolled fires. He said highway departments use them to burn grass in medians so it won't ignite accidentally from cigarette butts.

Fun

"Originally when we started off selling flamethrowers we were looking at this strictly from an entertainment purpose," said Quinn Whitehead, founder and CEO of Throwflame. He said flamethrowing is "exhilarating and leaves you grinning ear to ear."

Whitehead, who charges up to $3,200 for his handheld XL18 flamethrowers, said his customers discovered many other uses as well, such as using them as movie props or for clearing farm land or removing "pesky insect hives" or "torching their driveways and melting ice and snow."

Related: Elon Musk has sold out of flamethrowers

Zombie apocalypse

Tesla founder Musk said flamethrowers would be useful "when the zombie apocalypse happens." But Max Brooks, author of "World War Z," does not recommend flamethrowers for fighting zombies. In his book "The Zombie Survival Guide," he wrote, "Don't think a flamethrower and several Molotov cocktails are the solution to all your problems. In actual combat, fire can be as deadly a threat as it is a protector."

He said that the flamethrower "strikes people as the ultimate zombie eliminator" because it "can turn an undead crowd into a wailing funeral pyre." But he said the flamethrower would merely turn a zombie into "a shambling torch," and that "fire itself has no loyalty."