A sad person who gets a kick out goading an innocent person then calling this person a keyboard warrior! When in actual fact the person being goaded is just reacting to being called something derogatory and\or insulting!
Usually this is done through the text-based medium of the internet and usually under the cover of humour and usually split between threads or conversations to mask the accusation.
Person1: Hey you're an ass lol!
Person2: What? Did you just call me an ass? What the well you're a bigger ass! Was that supposed to be funny?