Blue moon

[Tink]

If something happens only once in a "blue moon" look out tonight!
It's gonna be a blue moon night.

[DianaB]

My daughter (college aged) was telling me that she found out at work that tonight was a "blue moon" and she was telling everyone that they needed to go out and look at it because it was going to be a "blue" moon!!!! Well, she had them laughing at her at work!!! I have to admit that I didn't know what a "blue moon" was until she told me.

[Mandy]

I dont know what a blue moon is, never heard of it here :)

[Tink]

A "blue moon" is when you get a second full moon in a single month.