adv. phr. , informal Without changing your feelings or opinion; without effect. Advice and correction roll off him like water off a duck's back. Many people showed him they didn't like what he was doing, but their disapproval passed off him like water off a duck's back.
LIKE WATER OFF A DUCK'S BACK
Meaning of LIKE WATER OFF A DUCK'S BACK in English
American idioms English vocabulary. Английский словарь американских идиом. 2012