in "The Frycook What Came From All That Space", where it was shown to be a very large restaurant, almost twice as large as Shloogorgh's. It is shaped like an unknown alien species, possibly the restaurant's founder or mascot.
What type of food Grub Demon sells is unknown, although it is likely to include junk food, as Foodcourtia is under Irken rule, and Irkens seem to live mostly on carbohydrates and large increments of sugars and fats. It is also possible that the restaurant offers a birthday party service for children, as a clear feature of the Grub Demon building is a giant party hat.
It is also seen in the game Nicktoons: MLB in Irken Field, as another place where its patrons can go to watch intergalactic baseball games while they eat.