What is a carbon dump?
Yeah you better be careful about shooting the bird. For starters, the person who offended you is a little bit screwy to begin with. Then, it might turn out that he has a gun, too.
Then, you will find out that "...this ain't Dodge City, and you ain't Bill Hickok."
Carbon dump- diesel PU truck dumping extra fuel in engine to smoke out someone they are passing on the HWY.