Bluechessium is a slang term in forums, where a user makes a very long post filled with quotations and replies to many other posts in the same thread.
Created when addressing a large backlog of unread posts. Sometimes mispelled as bluecheesium.
When the term is used on a forum, it's usually written in blue text.
"Excuse the bluechessium guys, I haven't had any internet for a week."