Estesna comes from the Russian word for naturally, written in a shortened, misspelled slang form that is common in casual online speech. The clip spread as a short reaction sound in chats and edited videos, valued because its meaning is clear even without context. Its brevity makes it easy to drop into memes, gaming clips and comment style edits, where a flat of course works better than a longer explanation. It remains used for sarcastic agreement rather than genuine confirmation.