Olm bu ne lan is a piece of everyday Turkish slang, with olm roughly meaning mate or dude and the full phrase asking what on earth something is. It became a popular reaction sound because the wording is short, punchy and instantly expressive, even for listeners who only catch the tone. Turkish creators have reused it across short-form videos, meme edits and reaction compilations to flag anything strange, broken or unexpectedly funny. Its appeal is not tied to one viral video, which is why it keeps working as a flexible, everyday reaction.