Hoping to save the Institute of Future Technology, Dr. Emmett Brown was about to secure a business loan from Mr. Friedman, who was shortly ran over by a DeLorean time machine driven by Professor Frink.
Without funding to continue, the Institute was sold to Krusty the Clown. Doc Brown was given a job at the park, which involved tearing tickets at the front gate.
Behind the scenes
The amusement park was the setting of The Simpsons Ride, which replaced Back to the Future: The Ride. The Institute of Future Technology becoming Krustyland was a nod to the replacement.