A term describing an individual who engages in activity with no regard for others' opinions or possible (perhaps even fatal) consequences. The activity often inconveniences others from a mid-to extremely high degree. The person engaging in the activity in question is usually, but not always consciously aware of his or her shit-assy doing(s).
Pat knowingly used the rest of the toilet paper in the bathroom and did not replace the roll. About an hour later, Roger sat down for a defecation, only to realize the bathroom was void of TP. He was forced to waddle down the hallway and retrieve more. In this example, Pat exhibits behavior of a mid-level shit-ass.