扑通

撲通
pūtōng
  1. (onom.) sound of object falling into water
  2. plop

CEDICT

onomatopoeic

Entry Composition

1 扑 pū
  1. to throw oneself at
  2. to pounce on
  3. to devote one's energies
  4. to flap
  5. to flutter
  6. to dab
  7. to pat
  8. to bend over
2 通 tōng
  1. to go through
  2. to know well
  3. (suffix) expert
  4. to connect
  5. to communicate
  6. open
  7. to clear
  8. classifier for letters, telegrams, phone calls etc