This sound is widely known as the losing horn from The Price Is Right, the long-running American television game show. Over time, the effect escaped the show and became a common reaction sound in meme edits, compilations and short videos. Creators use it because the cue is immediate: even without context, it signals failure, disappointment or an embarrassing miss. It still holds up online because the game show style is so familiar and the horn is short, clear and easy to place in a punchline.