Grammarphobia says it has no clue about the origins of "chumbalone"meaning an idiot, or stupid. https://www.grammarphobia.com/blog/2024/03/chumbolone.html

Maybe I'm an idiot, but I reckon it derives from the Italian ciambellone, like a big pound cake with a hole in the middle. Can anyone confirm?

Or could it be from coglione?