My Hero Academia centres on Izuku Midoriya, a quirkless boy who earns the hero name Deku and inherits the power One For All. The exact origin of this stretched 'you are my dekuuuu' voice clip is unclear, but it has spread as a playful fandom meme across anime TikTok and MHA edits, often dropped where creators might also use an anime ahhhh reaction gasp. It works because Deku fandom runs on affection: the line turns the hero's nickname into a pet name, and the exaggerated 'uuuu' ending sells the joke in just over a second.