I'm currently working on a Psych paper on Obsessive/Compulsive disorder. From what I've learned in my research, it appears that this particular psychological disorder is indicated by an obsession with a particular thing or idea, followed by a compulsion somehow focused on this thing or idea. For instance, if a person were obsessed with clearing the forum of BS threads, he or she might have a compulsion to post to various BS threads in the interest of attacking people in these threads.