The 'You... What Have You Done?' meme is a versatile reaction template used to illustrate a moment of extreme shock or comedic horror in response to a questionable action. While the phrase appears in various media, including a chilling scene with the Lich in Adventure Time and several popular webcomics like Shen Comix, the meme's power lies in its dramatic expression of disbelief. It is frequently used in the tech world to describe breaking code, in the food world for 'heretical' recipes, and in general social situations where someone makes a choice so baffling it triggers an immediate sense of impending doom.