When an expatriot showbusiness personality goes insane due to an inablility to cope with the strong and unique American culture they are thrust into via fame. Precursors are, freakishly odd quotes in interviews and outlandish behaviour in public.
Examples are William Shatner, Bono, Corey Haim, Mel Gibson, Margo Kidder, and Howie Mandel.
Coco "Did you watch the Two Coreys last night?"
Terrance "No, I hate shows about washed up celebrities. Why?"
Coco "Because Corey Haim totally Shatnered"