The phrase comes from everyday Turkish, where bunu duymamali means should not hear this, and the name Mert makes the clip feel like a private joke that escaped into public use. Short named reaction clips like this spread through soundboards, messaging apps and short video edits because they are easy to reuse in new contexts. The humor does not depend on a known show or film, it comes from imagining Mert hearing exactly what he was not supposed to, which keeps the sound useful for secrets, slip ups and teasing friends.