It Is Raining Cats and Dogs

It is raining very heavily

Strike While the Iron Is Hot

To act at the right moment when circumstances are favorable

Sophisticated

Having refined taste, knowledge, or experience of the world

Brain Teaser

A problem or puzzle that is difficult to solve

Bite the Hand That Feeds You

To act badly toward someone who has helped you

Cry over Spilt Milk

To be upset about something that has already happened and cannot be changed