Running so hard that you throw up during or immediately after a race. Also can be used to describe the "puke" that is ejected from the person and onto another runner.
He ran so hard during the cross countrymeet that he was ploofing nearly the whole time.
A dense object dropping into water, usually causing the water to shoot upwards making the 'ploomf' sound.
For best auditory effect, say outloud and with the back of your throat.
The onomatopoeic sound of a long turd satisfyingly dropping into the bowl....