Today's National Whatever Holiday is Multiple Personality Day.
Having a multiple personality disorder or dissociative identity disorder (DID) is a psychiatric diagnosis that describes a condition in which a person displays more than one distinct identities or personalities, such as an alter ego. Each of these personalities with its own pattern of perceiving and interacting with the environment.
There is a great deal of controversy surrounding the topic of DID. The validity of DID as a medical diagnosis has been questioned, and some researchers have suggested that DID may exist primarily as an iatrogenic (an illness caused by medical examination or treatment) adverse effect of therapy. DID is diagnosed significantly more frequently in North America compared to other areas of the world.