Etymology From ker- (prefix forming onomatopoeias imitating the effect or sound of a heavy object falling) + plunk (“dull thud of something landing on a surface”).
1
Informal A sound of someone or something falling and landing heavily.
If my life were a Saturday-morning cartoon, you would have heard a loud kerplunk as my stomach dropped. My poor starving stomach. It was under such stress already, and now this.2005, Michelle Tea, chapter 15, in Rose of No Man’s Land […], 1st Harvest edition, Orlando, Fla.; Austin, Tex.: Harcourt, published 2007, →ISBN, page 125:
Etymology From ker- (prefix forming onomatopoeias imitating the effect or sound of a heavy object falling) + plunk (“dull thud of something landing on a surface”).
1
Used to indicate a thudding sound.
We flipped to see who'd go first and I won, which meant Claudia had to dial. I called the number out loud for her, and inside me my heart was suddenly going "kerplunk, kerplunk, kerplunk," heavy as an elephant's feet.1986 November, Eve Bunting, chapter 7, in Sixth-grade Sleepover (An Apple Paperback), New York, N.Y.: Scholastic, →ISBN, page 41:
kerplunk
verb
Etymology From ker- (prefix forming onomatopoeias imitating the effect or sound of a heavy object falling) + plunk (“dull thud of something landing on a surface”).
1
Informal To make the sound of falling and landing heavily; to thud.