Someone who doesn't understand the etiquette common to chat rooms. This person will often offend others & even drive people from the chat room because they don't understand the "rules of the road". This often varies by the chat room involved. That which is acceptable in a chat room for general socializing may not go over well in a chat room for the depressed or folks who suffer anxiety.
A chatbrat will often use an emoticon to express negative feelings in a depression related chat room. When asked what's wrong, they sometimes repsond, "Nothing is wrong, why did you ask?", and will act as if their "actions" in a chat room only have the meaning they may intend. The other party will often be hurt & go to a different room, or leave chat altogether.
(n.) Someone who poses a personal or titillating question for general comment on a social forum, but refuses to answer that question themselves.
(v.t.) Leaving unanswered one's own question of this sort.
She keeps dropping questions about threesomes, but chatbrats them every time -- so we'll never know.