Plop Very Common

the noise of a rounded object dropping into a liquid without a splash

A sound or action like liquid hitting a hard surface, or an object falling into a body of water.

drop something with a plopping sound

drop with the sound of something falling into water

set (something or oneself) down with or as if with a noise

"He planked the money on the table"

"He planked himself into the sofa"

To make the sound of an object dropping into a body of liquid.

with a short hollow thud

"plop came the ball down to the corner of the green"

Acronym of Pattern Languages of Programs.