A Bristolian sexual act whereby the man is upside-down on his shoulders pushing his erect penis forward so that it is pointing towards the ceiling through his legs.
The female sits in a seated position on the man and leans as far forward as possible creating a kind of circular shape (the harvester).
The man after harvesting for some time then proceeds to push a turd from his anus, the perfect consistency is loose and bitty to mimic the spreading of the seed after the harvest.
ark at eee mind, him an is' missus only gone and dun a reverse combine harvester last night mind.