~ M ~

Make hay
Meaning: To take advantage of an opportunity or favourable condition
Example: Knowing that the project is postponed, colleagues make hay to finish all related tasks.

Make waves
Meaning: To change the current situation in a way that causes trouble.
Example: Staff decided to make waves and asked for a higher pay rise.

Monkey Business
Meaning: Silly behaviour or dishonest activities
Example: The boss has discovered some monkey business with the accounts.