"Five o'clock shadow" is a short beard on a man's face that has grown since the morning shave. Example: Peter has a very heavy beard - even though he shaves every morning, he gets a five o'clock shadow by lunchtime!
“Crack the whip” means “to use your authority to make someone else behave better or work harder”. Example: I was late for work three times, so my boss cracked the whip. If I’m late one more time, I’m fired! Get our apps for learning English:.