Look, I know how it sounds. But hear the equine out.

"It feels right to me, natural," says Trigger, a two-stepping stallion who has been ridden by nearly 500 women. "I don't know if I believe in reincarnation, but I have a deep feeling there is a horse soul inside this human body."

A subdivision of pet play (note: not bestiality), pony play explores the erotic world of beast and rider. It can be as simple as a piggyback or as elaborate as cantering through a storybook forest on the shoulders of a trail-blazing steed, naked save a bridle, bit and lunge whip. Some ponies don limb extensions (like stilts, but for your arms), and many model their behavior after certain breeds and personalities (Abyssinian, Clydesdale, punk-ass donkeys, etc.). There are even show ponies, arrogant little nags trotted around at BDSM conventions and judged on confirmation, tack appointment and performance.

While most pony play only lasts a few hours, some hardcore colts sign up for 24/7 sessions where the pony is completely dependent on his or her handler. In one of Trigger's five-day runs, he was tethered to a stall wearing only a horse tail hanging from a butt plug. Relying on a mistress to feed him (hay, carrots, a salt lick if he's lucky), clean out his stall (yep, he poops where he eats), groom his pubic hair and brush acorns and twigs off his feet after a run in the buggy was, according to Trigger, the "ultimate endurance test."

Paul and Emily, owners of Magic Pony Productions and editors of nine-year-old filly mag Equus Eroticus, head up a 20-acre ranch in Texas and say pony play is more popular now than ever. The couple points to mainstream exposure in Seabiscuit and Frasier, a saddled Madonna on the cover of W and through HBO's Real Sex. Even The Learning Channel wanted a piece of the action.

"A lot of people haven't come out of the stall yet," insists Emily, a former chemistry teacher and part-time pony girl who used to host a "Martha Stewart Primer" class on pony play at various camps and conventions. (FYI, Emily says Philly was once home to a healthy pony scene, but suspects it was driven underground when the cops raided BDSM clubs a few years back.)

"We're probably more vanilla than Playboy," adds Paul, noting that EE doesn't sell 1-900 ads or show full nudity. Even Trigger has trotted through Central Park and Provincetown in full horsey regalia. And while passers-by definitely stared, children also ran up to pet him, restaurant dishwashers fed him sugar cubes and tourists snapped pictures.

When I suggest he make a jaunt through Philly, he lets out a realistic high-pitched whinny—mostly because I agree to ride him through Independence Park once he gets here.

A horse is a horse, right?

Wrong, says Trigger. While he's been stabled alongside biological horses for extended periods of time, he has no interest in copycatting their sounds or body language.

"I don't want to imitate others," he explains. "I want to be my own horse."

Of course, of course.

Questions? Comments? Are you a sex collector? E-mail ashlea.halpern@citypaper.net. No phone calls.