The ㅠㅠ characters come from Korean online writing, where the shape mimics closed eyes with tears falling vertically. In chats it functions like a crying face emoji, signalling sadness, frustration, cuteness or pleading without needing a full sentence. As short-form video and soundboards spread the style globally, the spoken yuyu version became a standalone audio shorthand for the same feeling. It remains popular because it crosses language barriers, works instantly in memes and gaming clips, and turns minor setbacks into an exaggerated, shareable reaction.