Musak is a star in the "One Size Fits All" universe. "Muzak" is another name for "elevator music", easy listening and relaxing music that can be heard in elevators, shopping malls, train stations, airports or while a telephone caller is put on "hold".
Also note that the line "The White Zone is for loading and unloading only. If you got to load or unload go to the White Zone!" is a similar continuous drone than can be heard in airports and was referenced in Zappa's lyrics for Joe's Garage.