Idiom of the day :- (Like) water off a duck’s back
Usage, examples and definition of the Idiom :-
Ducks aren’t bothered by water because the oil in their feathers keeps moisture from reaching their bodies. Any water that gets on them runs right off. That has given us this expression, which we use to say that we are not annoyed by something. ‘School doesn’t bother Mary. To her, doing homework is like water off a duck’s back.’ Someone criticized Teddy, but he isn’t bothered. ‘ What do I care ? It’s water of a duck’s back to me,’ he said.