The act of driving very fast on a road or highway or street. Can also be applied to the act of pursuing a personal or professional goal. Originated in the 1960's, originally used in Brooklyn NY, describing a return trip from the Catskills in Upstate NY.
"I had to be back to light the boiler at the plant, so here I am barrel assing down the highway right past a cop." "He is determined, I mean he's barrel assing toward his goals."