Once in a blue moon: o que significa?

Hello there! Here's another idiom to help you to communicate better in English."Once in a blue moon". If something happens once in a blue moon, it happens very rarely indeed. 

Example:

John: How often do you go to church? Com que frequência você vai à igreja?

Mike: Once in a blue moon! Bem raramente!

That's it, see you!

Source: http://www.usingenglish.com

Categories: IDIOMS