Idioms and Phrases with when one's back is turned
when one's back is turned
When one is away or not looking, as in You can count on the children to misbehave when the teacher's back is turned, or I don't dare go on vacation; he'll take my job when my back is turned. Also see when the cat's away, the mice will play.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.