In Norse mythology, X symbolised heavy rain, while Y were associated with Odin the storm god, and therefore represented howling wind.

This led to a phrase which means raining heavily.

Id X and Y..

In times gone by, farmers would bring suckling pigs to market wrapped up in a bag. Unscrupulous ones would substitute a cat for the pig. If someone did X, the deceit was uncovered.

X is a commonly used phrase. 

Give me X.

Before anaesthetics were invented, injured soldiers would X to help them endure the pain of an operation/amputation.this led to the origin of the phrase X meaning to face an unpleasant reality.

What is the phrase (X)?