The line comes from 2011X, a fan-made incarnation of the Sonic.exe creepypasta that first appeared in the 2011 Sonic horror game and later spread through Roblox horror games and YouTube memes. 2011X is portrayed as a demonic version of Sonic who taunts and hunts the player, and lines like this one became shorthand for that menace. Horror creators pass the clip around the way they share the fnaf jumpscare scream and enemy spotted sounds, using it as a quick scare button whenever a video needs a villain to announce itself.