This sound is commonly shared online as a simple knocking effect rather than a clip with a clearly documented single source. Short 'toc toc' sounds spread widely on soundboards, messaging apps and meme edits because they are easy to reuse in skits, reaction posts and fake arrival jokes. Its lasting appeal comes from how instantly recognizable a double knock is: in less than two seconds, it can suggest a visitor, an interruption or a reveal without needing any extra context.