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.
He looted all nightlong, but when he came to his senses in the morning he began to feel bad, so instead of returning the loot he started plooting the river instead by throwing it all in.