The exaggerated OMG spelling with 1!1!1 comes from early internet typing, where holding Shift while hammering exclamation marks produced ones and signalled frantic excitement. That joke spelling carried into soundboards and meme edits, where a brief shouted reaction could stand in for disbelief without any context. It spread through short video edits, gaming clips and reaction compilations alongside other short reaction clips like the bruh meme, and it remains popular because the emotion is understood instantly, even muted spellings and captions preserve the same overexcited tone.