From Wiktionary, the free dictionary
From ker- + chunk.
kerchunk (plural kerchunks)
- A sudden heavy blow or thump.
- Synonyms: kerplunk, plunk, thud
1885, Woman's Board of Missions, Life and light for woman: Volume 15:But this kerchunk, kerchunk — that's the sieve motion.
kerchunk (not comparable)
- With a sudden heavy blow or thump.