Thursday, December 29, 2011

Once in a blue moon

How often do you see a blue moon?

Not very often?

Then something that happens very infrequently happens once in a blue moon.

E.G. 'Do you go to the movies very often?'

'Hardly at all; once in a blue moon.'

Of course, blue moon isn't just an idiom but a classic rock and roll ballad - like this: