Splat

According to the Merriam Webster online dictionary, the definition of the word "splat" is this:

a single flat thin often ornamental member of a back of a chair

(First known use 1833)

Which begs the question why the word is used colloquially as a sound effect, given that onomatopoeia doesn't apply. There are no sibilants or alveolars in a plop.

Still, when it comes to this whole "thirty (30) blog posts in thirty (30) days" thing, I seem to have fallen splat by day five. Which apparently means like the back of a chair.