The phrase duro como pedra is a common Portuguese expression for something extremely hard or someone who will not give in, and online it has become shorthand for exaggerated toughness. Clips using the Pato wording circulate as short reaction sounds because the meaning translates even when the listener does not speak Portuguese, especially with visual context. Its brevity helps it travel across meme edits, gaming clips, and group chats, where it is reused whenever a person, animal, or object appears impossibly solid or stubborn.