a sitting duck

sitting duck

Something that is unprotected and vulnerable to an easy attack. When my car broke down in a bad neighborhood, I felt like a sitting duck, just waiting to get robbed. We can't go into that area unarmed, we'd be sitting ducks!
See also: duck, sitting
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

a sitting duck

If someone is a sitting duck, they are in a situation where it is very easy to attack them or criticize them. A pilot performing this manoeuvre would be a sitting duck for a second enemy aircraft. Note: You can also use sitting-duck before a noun. When the planes reach the sitting-duck warships, the harbour is rocked by a series of huge explosions. Note: A duck is an easy target for hunters when it is sitting on the water or on the ground.
See also: duck, sitting
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

a ˌsitting ˈduck/ˈtarget

a person or thing that is very easy to attack or criticize: It’s always easy to criticize teachers; they’re just sitting ducks.
See also: duck, sitting, target
Farlex Partner Idioms Dictionary © Farlex 2017

sitting duck, a

An easy target. This expression clearly alludes to the ease with which a hunter can shoot a duck that is sitting still, in contrast to one in flight. It was transferred to other enterprises in the first half of the twentieth century.
See also: sitting
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
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References in periodicals archive ?
DON'T be a sitting duck - that's the message from the 'old bill' as they launch a quacking new campaign against car crime.
On the reverse will be safety reminders for the driver with the message "don't be a sitting duck".