An electronic version of coal rolling. "You can't tell me this is unhealthy, and I'm going to prove it!"

People "roll coal" it because it is kinda amusing to do it, and it is a middle finger towards people they perceive to be preachy.

I accidentally "rolled coal" in my 90s Landrover because I was in totally the wrong gear going up a steep hill. It was amusing in the way of "oh shit! I kinda just blew a load of black smoke in the driver face behind me".

Obviously, I don't do this deliberately.