What's the crowd sound people use after a burn?
It is a crowd "oooh" — a room of people reacting to an insult landing, rising in pitch and then falling away. The useful ones have enough individual voices audible to read as a real crowd rather than a canned laugh track, which is what separates them from sitcom audience sweetening.
Hear it
The gesture is older than the internet — it is what a live audience does — but short-form editing turned it into punctuation. It marks the moment as a scored point rather than merely a statement.
A subtle detail matters here: real crowd reactions start ragged, because people do not react in unison. Recordings that have been tightened or gated sound synthetic for exactly this reason, and viewers notice without being able to say why.
Start it a few frames before the reaction shot cuts in, so the audio leads the picture. Leading with sound is one of the cheapest ways to make an edit feel deliberate.
Commonly called
People search for this under a lot of different names — all of these find it here: