Language / Differences in Polish and English idioms [69]

I recently heard a funny idiom in Polish: "Once in a Russian year" which in English sounds Once in a blue moon :-)

I wonder where did it come from...

Oh, and one more: "A roll with butter" means "A piece of cake".
I think these are quite common idioms, both in Polish, and English.

Language / Differences in Polish and English idioms [69]

I'm a beginner in Polish, and I was wondering where can I find lessons with idioms for my level of proficiency.
Is there a book which presents certain idioms with e.g. pictures, descriptions?

Thanks malwinaflower, you intrigued me with the topic ;)