Here is from Paul Krugman's blog.
So, over the weekend we were told that our pass the popcorn moment — I mean, our long national nightmare — was over: Donald Trump would implode now that he had dared to question John McCain’s heroism.
(source)
I wonder what "our pass the popcorn moment" means. I know he meant by it "our long national nightmare", but I don't know what the "nightmare" has to do with "pass the popcorn".