You can't

As Mirandas hand toys with the erection in your pants the last of your resolve and self respect dissolve away and you give in to her advances. Your thoughts change from if you should to how you should and you vocalise this to Miranda. "How am I gonna fuck your ass?" you ask "We don't have any lube or anything?"

As if she had planned for this Miranda deftly unzips your jeans and slips them down your hips, before pulling your throbbing erection through the button fly of your boxers. Without hesitation she sinks her mouth on to it, her tongue swirling around your length as she quickly takes you deeper and deeper. You close your eyes and sigh in contentment from the sensation. This wasn't exactly how you'd pictured Miranda sucking your cock but you'll take it. Just when you're about to rest a hand on her head to encourage her she pulls back completely. "Is that lubed enough?" She asks, tugging your saliva coated dick lightly. Looking down you see your cock completely covered in a mix of her spit and your precum. "Yeah, that'll do." you answer.

"Good." Miranda replies before spinning around and bending over on the coffee table, resting her elbows on it as she presents her hindquarters to you like a bitch in heat. Her asshole still looks impenetrably tight, despite the earlier attention paid to it and as you kneel behind her you wonder how you'll ever slip your dick inside. While you think you remember that Miranda was going to give this perfect little ass up to Tom and his even thicker cock, it seems impossible that he could ever fit. Your thoughts of Mirandas slutty words to him fill you with anger and you suddenly decide that you don't care how it feels for her.

Lining your cockhead with her virginal rosebud you grab Mirandas hips to steady her before shoving your saliva coated cock as deep into her as it will go. To your surprise Mirandas asshole accepts your cock fairly readily, her improvised lube proving sufficient and you manage to bury your full length in one steady movement. Miranda only let out a gasp as you sank into her, while grabbing on to the far edge of the table tightly.

When it's time to pull back you encounter your first problem. It feels like Mirandas ass won't let go of your cock and now you're wedged inside her. Holding her hips tighter you try again to pull back but all you get for your efforts are more pants and moans from Miranda. Finally you pull back with your hips and push forward on hers simultaneously and with a herculean effort you pull your cock free like Excalibur from the stone.

Taking a breath to recover Miranda begins to push back against you and you start fucking her ass in earnest. The first few thrusts struggle in a similar way to the first but over time Mirandas ass becomes looser and you feel less and less resistance as you pull out. The resistance is decreasing but Miranda is growing louder and louder, half shouting "fuck" under her every breath to greet your every thrust, but you're just getting started. You smack her ass as you begin to pound her even harder, your hips moving like a dynamo as you fuck her recklessly.

She soon stops even trying to conceal her feelings as her moans and muttered curses develop into full blown screams, of pain or pleasure you're not quite sure. It doesn't matter, you're not stopping either way. After everything she just made you watch this it the least she deserves. Regardless, her moans and the hot tightness on your cock are bringing you to orgasm but you only increase the pace of your thrusts, and you decide that you're going to creampie her pert ass.

No need to warn her, you think, it's not like she can get pregnant from her ass. You fuck her with a few more staggered thrusts before hilting your cock completely as you explode inside her, pumping her with your cum. "F-fuuuuuck" she moans as you dump a load inside her, before her arms give out and she collapses completely on to the table, shuddering in pleasure. Even as you cum her asshole tightens and squeezes around your shaft, as if it was milking your dick.

After what feels like a blissful eternity Mirandas asshole pulls the last of your cum from you and you gingerly withdraw your deflating prick from her stretched hole. Leaning back on the couch you admire your handiwork as Miranda shudders on the table with your load starting to ooze from her ass. Everything is quiet for a moment save for Mirandas panting but inevitably the peace is broken.

"John?" Miranda asks