One who constantly steps over "the line" whatever that line may be. This has the effect of forcing you as an observer to set him or her straight with physical force or the threat of physical force.
Then Charlie Murphy proceeds to kick Rick James' ass because he's gotta check that shit so it don't happen again, forcing him to stop being a habitual line stepper.
By Bernadene
Habitual Line Stepper
One who always goes over the line. One who always goes too far and exercises no apparant regard for the consequences. Term was coined by Charlie Murphy on Chapelle's Show when describing the antics of Rick James.