The sound comes from the world of SCP, the collaborative horror fiction project that began on the SCP Foundation wiki and inspired indie horror games such as SCP Containment Breach, where keycards open containment doors. Players hear the scanner beep when they gain access to new areas, so the clip became shorthand for clearance and hidden danger. Clips of the sound spread through SCP gameplay videos, fan edits and roleplay content, and creators still use it because it instantly signals an SCP setting without any dialogue or explanation.