The term 'Nightmare Fuel' refers to any content—images, videos, or stories—that is so deeply unsettling, creepy, or uncanny that it could theoretically cause nightmares for the viewer. While it originated as a slang term on early internet forums and imageboards like 4chan and Reddit to describe 'cursed images,' it evolved into a popular meme genre used to react to terrifying visual glitches, weird creatures, or unnerving childhood media. Today, the Nightmare Fuel meme template is used to satirize the fear of the unknown, often pairing a disturbing visual with a relatable caption about late-night anxiety or surreal encounters. It thrives on the 'Uncanny Valley' effect, where something looks almost human but is just wrong enough to trigger a primal fear response.