Yalan mı is a common Turkish expression used in everyday conversation to question whether something is true, and it has travelled into online video culture as a short reaction sound. Because the phrase is brief, expressive and easy to recognise, creators reuse it to puncture boasts, excuses and unlikely claims without needing a long explanation. It fits naturally in Turkish memes, reaction edits and short-form videos, where a single sceptical question can carry the joke. Its popularity comes from that shared cultural shorthand rather than from one film, show or viral clip.