Place it just after the reveal of the mystery substance, then follow it with a bruh reaction while the camera stays on the mess, and finish with a fail sting once the bad idea is confirmed.
关于此声音
This short French voice clip, lasting about three seconds, asks what a strange material is, whether it is shit, and then answers that it is Kloug. The rapid questions build confused disgust before the flat final name lands as a joke. It works as a baffled reaction to something gross, messy or impossible to identify.