This sound does not have a clearly documented single-source origin from a specific film, show or game. Online, "mlem" is widely used as a text version of a tongue-out or licking noise, especially in pet memes and reaction edits. Short repeated mlem audio clips spread across soundboards, meme compilations and social video apps because they are easy to understand without dialogue. It remains popular because it instantly signals cuteness, hunger, mischief or exaggerated thirst in just a second or two.