Plop

Definition: (from dictionary.com)
-verb (used without object)
1. to make a sound like that of something falling or dropping into water
2. to fall with such a sound
3. to drop or fall with full force or direct impact
-noun
6. a plopping sound or fall
7. the act of plopping

Examples:

"The dolphin flipped in the air and returned to the water with a plop."

"I got home from work and plopped on the couch until dinner was ready."

Origin: (from etymonline.com)

"1821, imitative of the sound of a smooth object dropping into water."

Awkwardness rating: 5

Best to plop at home instead of the office. (imageshack.us)