The Forever Bag was said to have originally belonged to a great wizard before it was stolen from him by the fabled King of Thieves, Mesclabar. Over the years, filled with the amassed fortune of its various owners, the Forever Bag was repeatedly stolen by various thieves until it came upon the hands of the gentleman pickpocket Tookit. Using the Forever Bag as a mobile base of operations, Tookit used the item to store his collection of stolen items while sneaking the young thieves he tricked into his service to stealing the contents of whatever building he placed them in.WilyKat and WilyKit first learn about the Forever Bag when they confront Tookit to get their stolen items back. But upon learning that the raccoon played them for his agenda, the twins convinced Tookit's three other recruits to turn against Tookit by fooling him into taking a fake copy of the bag while tricking the raccoon into clearing their names of the crimes he framed them of. After Tookit ends up getting caught red-handed and unable to escape the Constable, Wilykat and Wilykit become shared owners of the Forever Bag.
In What Lies Above, Part 1, Kit and Kat used it to sneak in some of their own food for the meal.
- The magic word used to open the bag is a nod to "Rankin/Bass", the name of the company which produced the first Thunder Cats television show.