go behind back

go behind (one's) back

To do something in one's absence. The phrase typically suggests wrongdoing or deceit. I can't believe you went behind my back and gossiped about me! Tom will be upset that we've gone behind his back and made the decision.See also: back, behind, go

go behind someone's back

 1. Lit. to move behind someone; to locate oneself at someone's back. The mugger went behind my back and put a gun to my spine. Bob went behind my back and pushed me through the opening. 2. Fig. to do something that is kept a secret from someone affected by it. I hate to go behind her back, but she makes so much trouble about things like this. Please don't try to go behind my back again!See also: back, behind, go