Italians have some funny ways of saying that something is impossible. One way is to say that the impossible task is like trying to asciugare i scogli, or “dry the cliffs”.
This expression sure gets it right in the “impossible” category, and the vivid image made me remember it instantly. I just saw myself, kitchen towel in hand, trying to dry the rock sides of a steep cliff in between surges of oncoming waves. Not. Very. Feasible.
There’s another one, though with less initial impact: like trying to cavar sangue da una rapa (draw blood from a turnip).
The one that makes me laugh the most is… like trying to legare un cane con le salsicce (tie a dog with sausages)!