Your slave thinks that because she has the pussy, she has the power. Even though you're giving the orders, she will be under the false belief that she holds all the cards. The order for her to "Spread Wide" will wake her up from that dream. 

With my slave, I always start with the order to "Spread." This puts her in a good position of vulnerability. She's on her back, her pussy is exposed, and whoever wants to can fuck her with no problem. Yet she still thinks she has some power. After all, a bitch can get a lot of promises when she's on her back with her legs spread. But when you order "Spread Wide," she realizes that her cunt is no more than a fuck toy for you, something to be used, abused and forgotten, like a piece of trash dropped on the side of the road.

I like to use Spread Wide in public places. I order her to wear a sundress with no underwear. Then we drive out to a nature area that's lightly used by hikers, but not abandoned. We'll head out into the woods and I'll station her within sight of a hiking trail, but partially hidden by some brush. After performing a degrading inspection on her (I like to use a stick off the ground as a bit, and stuff leaves into her crack and slit), I'll order her onto the ground in the Spread position. After further probing her pussy and ass with my fingers and whatever other items at hand, I pull her dress up over her head, leaving her head covered and her body exposed. Then I watch the path for a willing participant.

Last time, I found a senior citizen slowly strolling the path. After explaining that my wife was in the woods, naked and waiting for an audience, he agreed to help me out. If the sight of her dirty, nude body laying in the dirt shocked him, he didn't show it. Her pussy by now was fully swollen, with drops of her juices gleaming in the sunlight. Her nipples were fully erect, as she no doubt was imagining what this stranger looked like, and what I would let him do to her. I spoke with him for a while, telling him what a slut she was, and pointing out interesting aspects of her body, such as the exceptional length of her nipples when she's excited. When I informed him that she would be confessing her sexual sins to him, he asked whether he could get himself off during it. No problem, I replied, imagining the dismay that my slave was probably experiencing. 

On my orders, she tells him, from beneath the veil of her dress, about her favorite sexual position, how she loves to get it in the ass, and about eating cum for breakfast the past weekend. By now he's jacking off hard, having borrowed some lubricant that my slave is required to carry in her purse at all times. And that's when I remember my manners. "Spread wide" I order her. Immediately she spreads her legs wider apart and, reaching down with her fingers, spreads her pussy lips apart so our guest can see right down into her dirty, steaming cunt hole. Moving her arms has caused her dress to partially cover her breasts. "Uncover your tits, you fucking slut whore!" I yell at her. I begin to apologize to our guest for her poor manners, but I can tell he's ready to blow his load. At my gesture, she steps forward between her open legs and immediately lets loose a stream of cum that splashes up and down her slutty body. He even manages to dribble a few drops into her still open cunt hole, to join the steaming liquids already gushing around in there. 

I keep her in that position even as he puts his pecker away and we talk some more about my efforts to train at least one slut the right way. And as he heads back to continue his walk, she lies there, cum covered in the dirt, her lips splayed and her hole excavated, a cunt who knows just where she fits into the order of things.