když se (kdo) nedívá, za zády koho
Of course, you must make sure you protect the baby from a toddler who pinches or slaps or tries to tip her out of the pram when your back is turned.
He is often so busy that the less powerful males are able to disappear into a corner and copulate with his favourite females while his back is turned.
They are quite happy to question you, though, and are not averse to having a look through your personal items when your back is turned.
(BNC-B)
» THE HUMAN BODY