Place it at the peak of a slapstick sequence, after a build-up sound and just before the reaction, then follow it with a punch sound for the follow-through or a metal pipe clang when the object keeps falling.
About this sound
This two-second cartoon smash is a short impact effect made for slapstick collisions, packing a sudden crash into one quick burst. It feels sudden, silly and over the top, like a character getting flattened in a single frame. It comes from Hanna-Barbera cartoons, including Atom Ant, where it punctuated falling objects and clumsy crashes.