Wonderhoy is the signature catchphrase and pose of Emu Otori, a hyperactive and cheerful character from the mobile rhythm game Project Sekai: Colorful Stage! feat. Hatsune Miku. The term itself is a nonsense word created by Emu to represent feelings of pure excitement, happiness, and friendship. The meme typically features an image of Emu with her arms spread wide and a beaming smile, capturing her chaotic yet wholesome energy. It has transcended the gaming community to become a universal reaction meme on platforms like Twitter, TikTok, and Discord, often used to express overwhelming positivity or to ironically signal impending cheerful chaos. Its popularity is fueled by Emu's infectious personality and the distinct, high-pitched vocal delivery of the line in the game.