Chatheimer's is a condition in which one looses the ability to focus on chatroom conversations. It may also be used for someone who comes into a regular chatroom and has said something about someone, but later "can't remember saying that", as to avoid blame placement.
"Did you talk to fjka42? He said, that you said, blah blah blah" "Yeah, I talked to him, but he didn't know anything about saying that. He must have chatheimer's."