Actionitis is the infectious disease that comes with listening to too much music by the band Action Item, and in effect becoming obsessed. Symptoms may include random outbursts of AI songs, uncontrollable checking of the AI Facebook, Twitter and MySpace pages, and constant swooning over any of the band members. There is no current cure known to man.
Person 1: Did you signup for the Action Item fan club forty seven time???
Person 2: Yep. I have Actionitis. *plays song by Action Item"
Person 1: OMG. Now I've got it too!