Swishish
On the first panel, a Triangle-person is walking towards a forest visible in the distance: “Polish laguage is superbly suited for conversing with trees. Let me demonstrate!”
On the second panel, the same Triangle-person is standing next to a large leafy tree, holding hands to their mouth and saying gently: “Swishis-shoom-shlehleshchontsich-leeshchee?✵”, and the tree responds “Yeshhh”. The text is translated below: “✵Do you hear the hum of rustling leaves?”
Next time you meet a Pole, try saying something like “Shshhhhshhhhchsshhshchchshh” and see if they can pick some meaning out of it.