The term 'serial adder' has a special meaning in the world of LiveJournal. Understanding this node requires a basic understanding of how the LiveJournal community works.

LiveJournal users have the ability to set up 'friends lists' made up of other journals, communities, and external RSS feeds. Being listed by someone else as a friend allows one to read protected journal entries and obviously implies some sort of relationship. Also, if someone else lists you as a friend, that account name will show up on your profile page under the 'Friend of' section.

It's this last point that can freak people out. Some LiveJournal users are fiercely territorial of their friends lists, becoming very angry when people start reading their journals regularly without 'permission'. Serial adders relentlessly add these types to their own friends lists, thus becoming a new species of troll.

For April Fool's Day 2004, the LiveJournal staff created a fake account called "lj_serialadder" who appeared to have every single user on its list.