The phrase is everyday Russian for I am going to sleep, transliterated as ya spat poshyol or ia spat poshiol from the Cyrillic spelling. As a short voice clip it spread in Russian speaking chats and meme edits, where its brevity makes it easy to drop at the end of a conversation. English speaking creators picked it up as a reaction and goodnight sound, often pairing it with a snore mimimimimimi clip afterwards. It remains popular because the tired delivery works even if listeners do not understand Russian.