MissingNo. (short for Missing Number) is the most famous glitch in video game history, appearing in Pokémon Red and Blue when the game tries to access data for a non-existent Pokémon species. Represented by a distinctive L-shaped block of scrambled pixels, it became a cultural phenomenon for its ability to duplicate items or corrupt save files. In the world of memes, MissingNo. represents chaos, technical failures, and the eerie feeling of breaking the simulation. It is frequently used to symbolize something that shouldn't exist or a person who feels out of place in a structured environment.