teaser pony

A teaser pony prevents the mare from damaging a prize stallion. The teaser is led out to the pasture. If the mare is violently unwilling, there’s no danger of injuring a horse whose bloodlines make him valuable breeding stock. If the mare presents, the teaser is led away, and the stud is brought in to mate with the stare. So basically is a "test horse" used to give other male horses boners, and a test bang. It can act as a great insult.