check your six

check (one's) six

To look behind oneself, typically by looking over one's shoulder. "Six o'clock" is a military term referring to the area behind oneself. Make sure to check your six, in case someone tries to follow you.
See also: check, six
Farlex Dictionary of Idioms.

check your six

tv. look behind you (where there may be danger). (see also on your six. Refers to six o’clock as being behind one, as if one were facing twelve o’clock.) Check your six, bud. Some gangsta’s getting close to your wallet.
See also: check, six
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • check (one's) six
  • watch (one's) six
  • get behind
  • get behind (someone or something)
  • get behind someone/something
  • get behind something
  • take cover
  • hide behind
  • hide behind (someone or something)
  • drop out of sight
References in periodicals archive
* Mentally check your six again when you shout "clear" before starting your engine.
If you decide to stop or turn, check your six again before adding throttle.
Blowin' in the wind: the FAA calls prop wash "thrust stream turbulence. " Whatever you call it, ignore it at your peril
But, I will now be aware of the fact that, "It can happen to me!" Readers be alert and "check your six" before you send in a check!
Scumbag alerts work
Check your SIX numbers with the numbered boxes on our Sunday People one-armed bandit.
JACKPOT OF GOLD
Check your SIX Hit The Jackpot numbers with the numbered boxes on our Sunday People one-armed bandit.
HIT THE JACKPOT!; Have these numbers won for you on the one-armed bandit?