From Wiki:

"Figging is the practice of inserting a piece of ginger root into the anus or vagina. Originally applied to horses as a form of deception as to the horse's condition, it now most commonly refers to a practice in BDSM."

No deception about horse's condition. When showing Tennessee Walking horses, it was preferable for the horse to have its tail raised while being ridden around the ring. The handlers would have their colored grooms chew on ginger root, and stick it in the horses ass, so it would raise the tail to try and poop. Purely aesthetic, no deception.

My old man always used to wonder, "If it burns the horse's asshole, what's it do to the nigger's mouth?"