The first time I heard of anything like this, someone was taking duct tape and creating an opening by taping the plastic strands of an outdoor chaise lounge, allowing a guy to lie face-down in the lounge and have himself attended to from underneath.
This takes it one step farther. Does anyone know of any providers who have similar equipment, whether designed or jerry-rigged?
http://milkingtable.com/main.html
Warning: Definitely NSFW.