Meaning: be badly affected by a situation where two people or group are arguing with each other.

Example:
When parents fight over trifles, their children are often caught in the crossfire.

Meaning: quarrel; have a disagreement.

Example:
Every day at 6 PM. the Jenny and Eliza crossed swords for watching their favorite show.

Meaning: to reach the highest point of success.

Example:
1. The music band comprising engineering students is currently on the crest of a wave, with a launch of new album it has planned for next year.
2. He has reached the crest of the wave with his new book.

Meaning: to hurry something up. To start working on something right away.

Example:
1. The laundry man better get cracking with our clothes else we will miss the event.
2. I better get cracking for my interview tomorrow.