The sound comes from Law and Order, the long-running American police procedural and legal drama that began on NBC in 1990, where the short sting played whenever the story jumped to a new location or time. Viewers nicknamed its two-note pattern the doink doink, and as clips and soundboards spread online it became shorthand for a legal or investigative twist. Creators still reach for it because it is instantly recognisable even without any dialogue, instantly framing an ordinary moment as a case taking a serious turn.