Longhorn was Microsoft's codename for the operating system that eventually became Windows Vista, and its test builds in the early to mid-2000s included their own set of system sounds for connecting and disconnecting hardware. The USB out chime comes from that era of unfinished, experimental Windows design, which is why it sounds slightly different from the familiar Vista and Windows 7 alerts that followed. Soundboard users have kept it alive for retro computing videos, tech humour and edits where a modern disconnect sound would feel too polished.