Human pony play, also called ponygirl or ponyboy play depending on the sex of the participants, is a form of roleplay where one person (usually a woman) acts like a pony or horse, while a sexual partner acts as a caretaker (or a stallion). Some authorities classify this is an animal transformation fantasy, though ponygirl play is far more common than any other form of animal transformation play. The limited evidence that is available suggests that the fantasy and practice may be somewhat more prevalent in the U.K. than elsewhere.
An endless array of bit gags, bridles, saddles, tack (harnesses), butt plugs with tails, "hooves" that are worn like gloves and boots, and related items are produced and sold commercially to those who wish to act out such fantasies.
Ponygirl play is sometimes considered a bondage game or BDSM practice, particularly as the bridle is often a gag and typically the arms are restrained in some way. This is not always the case, however; like almost any other sexual game, it can be acted out by itself or in conjunction with other sexual elements.
While there are a few men who have "ponyboy" fantasies, the "human pony" is a form of sexual play primarily of interest to women. That said, ponygirls occasionally appear in the photography in sexual literature marketed to men.