watch your back

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watch (someone's) back

To be willing and prepared to help or defend someone; to look out for someone in case they need assistance. Don't worry about those thugs, buddy. I'll watch your back if they ever come bother you again. You can always rely on your parents to watch your back.
See also: back, watch
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

watch your (or someone's) back

protect yourself (or someone else) against danger from an unexpected quarter.
See also: back, watch
Farlex Partner Idioms Dictionary © Farlex 2017
See also:
References in periodicals archive ?
"Watch Your Back and the film were inspired by my life story - I was a doorman for about 10 years during the 1980s for pubs across Coventry.
A prison officer was warned 'watch your back' after a colleague made a complaint against her which was later said to be forced.
Hope you rot!" She later added: "Watch your back, we've got you on camera.
Sandra said: "With Meryl, when this whole thing started, I left her a voice mail going, 'You've got to watch your back. I'm gonna take you down.' Then she sent me dead orchids and told me to die."
ONE TO WATCH: Watch Your Back (left) is Garry's nap at Ayr
But yesterday, her partner Nick Kroll jokingly posted on Twitter: "Hey Bono, watch your back."
WATCH YOUR BACK: Jim Furyk could be letting Tiger Woods know about the threat to his No.1 role
The singer claims his message collection includes one that warns, `You better watch your back, because you are seriously f***.'
I want to get more involved in this cause, so I'm going to read all the newspapers while I'm in Athens planning my wedding." Watch your back, Kofi Annan.
WATCH your back Gameboy, another new handheld device is after your gaming crown.
Better watch your back Joni, no-one messes with the big 'M'.
He says: "Anyone could have wandered in, so we needed adequate men on the door." Quite, Michael, what with all those investment bankers living nearby, it's best to watch your back (not to mention the silver).