A sexual act involving a couple. One is the horse or pony and the other is the dominating equestrian. Props include equestrian boots, fake tail, whip, coconut shells, hay, a saddle, and other necessary s&m items. The Dominating equestrian would ride the "horse/pony", similar to the real life situation.
Katelynn rode Jerry like the German pony he is, with tail, saddle and all during horseyplay.