Keep your head on a swivel

Meaning

A warning to stay extremely alert and aware of your surroundings. It is often used in situations where you could be blindsided by an opponent or an obstacle.

Cautionary, intense

Used in a sentence

• When you are walking through the city at night, keep your head on a swivel.
• The quarterback was reminded to keep his head on a swivel against that defense.
• In this office, you have to keep your head on a swivel if you want to succeed.