This idiom means "sometimes, rarely"
Once in a blue moon
This idiom means "to reveal your real character"
to show your true colors
This idiom means "to feel sad, to be morose"
to feel blue
______ with envy
green
This idiom means "to owe money"
to be in the red
______ blood
blue
Once in a blue ______
moon
This idiom means "lots of documents, unnecessary bureaucracy"
red tape
This idiom means to criticize someone while having that same fault yourself
pot calling the kettle black
The _____ is always greener on the other side
grass