situational vs dispositional
if someone sees a stranger doing something, someone assumes it's b/c of the stranger's disposition. (ie. the stranger is a "bad person".)
if someone does something, someone assumes it's situational.
psychology
quite frankly, sometimes I am a jerk. besides, what's the definition of "jerk" anyways?
furthermore, after interacting with someone for long enough, pretty much everyone is a jerk.