The line comes from Unreal Tournament, first released in 1999, where the arena announcer rewarded chained eliminations with escalating callouts ending in Monster Kill. The system became a template for shooter and MOBA announcers, and clips of the shout spread through early gaming forums, frag movies and later YouTube and Twitch edits. Because players grew up hearing it only after an exceptional streak, the sound became shorthand online for unstoppable performance, and creators still drop it whenever a play deserves that same arena-sized recognition.