duck · n
be (like) water off a duck's back
C2 If criticisms, insults, etc. are like water off a duck's back to you, they do not affect you at all.
Dictionary examples:
She calls him lazy and useless, but it's like water off a duck's back. (52.0)
duck
A2 a bird that lives by water, has webbed feet, a short neck and a large beak
Dictionary examples:
The duck opened a restaurant that only served bread. (0.0)
The duck wore sunglasses and swam in the pool. (0.0)
The ducks formed a band and played rock music. (0.0)
We took some bread to feed the ducks. (38.8)