Asexual Band Geeks are a clique at North Shore High School.
They are seperate, and quite the opposite clique from the Sexually Active Band Geeks. They are defined as such by Janis Ian in a map of the North Shore Cafeteria intended for Cady Heron's use. Janis does not mention them when she gives a verbal description of the map in the film.
Judging by it's name, the clique was mostly formed by students who don't have any sexual feelings or associations.