plop 
(plŏp)
(plŏp)v. plopped, plop·ping, plops
v.intr.
1. To fall with a sound like that of an object falling into water without splashing.
2. To let the body drop heavily: Exhausted, I plopped into the armchair.
v.tr.
To drop or set heavily: plopped the child into the stroller.
n.
A plopping sound or movement.
[Imitative.]
plop adv.