Kamisan, English contains many colourful expressions which mean "that would never happen." "It isn't millenium day!" is one of them though it is relatively new, used since the millenium of course. Also, "When pigs can fly," "When hell freezes over," and so on. Since millenium day only happens one day in one thousand years they were implying that there was little or no chance it would happen today.
Hi, ハリsan
Thank you for your comment.
I agree your comment and English is falstaffian.
But it seems strang wording for Japanese.
Do Japanese people have to adjust to the English wording for worldwide activity?
I teach Japanese language a internet school but almost students want to learn English.
Why a lot of people want to learn English? The person who ask such question is also learning English.........