keep six 

To hang back and watch out for somebody when they are going into a potentially dangerous situation. As in before a large illegal transaction, or while conducting a robbery.

Has nothing to do with police being 5-0. Actually derived from military communications. When an infantry squad is moving, one member may be assigned to "watch the squad's 6", meaning their 6 o'clock (behind them).

Alright guys, there's supposed to be no guns inside the pool hall, so you stay out here and keep six for me. If I you hear shots or I'm not out in 20 minutes, come in blasting.

keep six by Wasteland Soldier January 29, 2007

KEEP SIX 

to watch over; be a lookout for

"stay by the window and keep six for any cops."

KEEP SIX by bmoc November 6, 2003

Keep Six 

to be on the lookout

For example a robbery is being committed and one robber tells the other to go outside and KEEP SIX

Keep Six by SonnyStunner March 12, 2012

keep six 

To have a person's back. Derived from military. Also serves well for people who grew up in the ghetto and not necessarily causing trouble purposefully. Also something your girlfriend might say if she needs to pee in public and is decent enough to find a nice tree

Hey buddy , I really gotta go and the store is half an hour walk away... can you keep six?

keep six by zoidums August 5, 2016

KEEP SIX 

To keep a look out for police, derived from cops being 5.0, so six means you're one up on the cops.

I'll park here and roll this up if you keep six!

KEEP SIX by vijay December 3, 2003