One of the numerous clubs that is to be found in cities like Rome. Usually full of Americans, which is not a good sign if thery're abroad.
Caos club is located in Via della Paglia in Trastevere, Rome, and should not be considered as a place to go, unless you're aiming at Americans which haven't experienced their 21st birthday yet, OR if you're not inclined to meet colored people.
Anyhow, this is the place where you go if you've enrolled at St. Johns University, Rome, and - as a corollary - haven't yet completed all of the prerequisites of a grown-up.