The scream comes from Team Fortress 2, Valve's class based shooter released in 2007, where each class has distinct critical death sounds. The Spy's version became a favourite in machinimas, Garry's Mod videos and soundboards because his normally suave voice breaks so completely. Like the ROBLOX oof, it turned a routine in game death noise into a reusable reaction shared far beyond its original players, and it still appears in meme edits whenever a sneaky character is caught and eliminated.