The 'Beach or Door' meme is a famous optical illusion that first took the internet by storm in 2018. It features a photo that, depending on how you rotate it or perceive the lighting, either looks like a close-up of a blue door frame against a white wall or a serene beach scene with a turquoise ocean and sandy shore. In reality, the image is a rotated photograph of a beach, but the ambiguity fueled endless debates across platforms like Twitter and Reddit. It is commonly used to illustrate the concept of subjective reality, showing how two people can view the same evidence and see entirely different things, making it a staple for philosophical jokes and online arguments.