Water off a duck’s back
This expression means that you can insult or criticise someone but it doesn’t affect them in the slightest.
Ducks have oily feathers and water can’t get through them, so water runs off their backs. In the same way, some people don’t allow criticism to get at them and upset them. Instead they leave it go like ‘water off a duck’s back’.
- The newspaper wrote terrible things about John but it rolled off him like water off a duck’s back.
- Susan critisised Tom’s play so much that it really hurt the actors. But to Tom it was like water off a duck’s back.