Plop

[Sarah]

To fall, drop, or move in any way, with a sudden splash orslap, as on the surface of water.

[Sarah]

The sound one makes when one drops a ploppy-poo into a body of water.

[Gregory]

Plop- Is to [lay] or [sit] very comfortably for an [excessive] period of time.

[Donald Trump]

A short sound as of a small, solid object dropping into water without a splash.

[Justin Bieber]

a soft sound like that of something solid dropping lightly into a liquid: