The ooh comes from the alpha era of Minecraft, the sandbox game released in early form in 2009 and developed through alpha in 2010, where it played whenever the player took damage. It became closely associated with the default player character because players heard it constantly while exploring, mining and fighting mobs. As Minecraft videos grew on YouTube, the sound became nostalgic shorthand for early gameplay. After later updates replaced it with less vocal damage sounds, creators kept reusing the original as a meme effect for exaggerated, low stakes pain.