what's the matter

get what's coming to one

To experience the consequences of one's actions.

grey matter

Brains; a person's ability to think.

matter at hand

The current issue, which requires immediate attention.

matter of course

A natural or logical outcome; perforce.

matter of life and death

An extremely urgent matter.

matter of time

An inevitable result; something that is bound to happen.

what's cooking

A greeting, similar to how are you?; what's happening?; what's up?; what's new?

what's eating

What is wrong with...? What is the problem with... (somebody)? Inquired regarding somebody who seems upset, worried, angry, etc.