Conservatives’ disgust for the Obama administration and liberals have manifested in many ways, but one of the most visible forms of political and cultural protest is nearly impossible not to see, or smell.

Known as “rolling coal,” some diesel truck owners have modified their engines and vehicles so they can blow thick, black, acrid clouds of exhaust into the air while driving down the road.

Some rolling coalers enjoy cutting lose near hybrid car owners, claiming the plume of smoke is a form of “Prius repellent.”

The engine modifications that produce the black clouds (which amounts to pumping extra fuel into engines) are not cheap. The cost can reportedly run between $500 and $5,000.

Some conservatives have expressed outrage at the U.S. Environmental Protection Agency’s (EPA) clean-air policies, claiming they represent another attempt by liberal do-gooders to take away people’s rights.

“I run into a lot of people that really don’t like Obama at all,” one Wisconsin seller of engine-modification kits told Slate. “If he’s into the environment, if he’s into this or that, we’re not. I hear a lot of that. To get a single stack on my truck—that’s my way of giving them the finger. You want clean air and a tiny carbon footprint? Well, screw you.”

Diesel exhaust is one of the worst toxic pollutants in the U.S. and results in 21,000 deaths annually, according to the Clean Air Taskforce.

“I’m not a scientist, but it couldn’t be too horrible,” a South Carolina diesel mechanic who has been rolling coal for 12 years told Vocativ. “There are a lot of factories that are doing way worse than my truck.”

“It’s bad for the environment,” admitted another coal roller. “And you can cause a wreck, but everything else about it is pretty good.”

One diesel protestor, Sean Miller of Arizona, confessed to Slate that some people, namely men, do it because, “It’s just a testosterone thing. It’s manhood. It’s who can blow the most smoke, whose is blacker.”

But Miller gave it up because eventually he became embarrassed by the amount of pollution he was pouring into the air, and because it was costing him extra fuel, and thus money, while sticking it to...whomever.

The EPA, meanwhile, has stated that the practice is clearly illegal, which it says is supported by two paragraphs on the enforcement page of the agency’s website.

-Noel Brinkerhoff

To Learn More:

Rolling Coal (by David Weigel, Slate)

“Rollin’ Coal” Is Pollution Porn for Dudes With Pickup Trucks (by Elizabeth Kulze, Vocativ)

Diesel (Clean Air Task Force)