Then I spin you around so you're facing the window. You put your hands against the glass. My hands reached under your shirt and grabbed your breasts, massaging them and then pinching your nipples. I wonder if anyone outside can see you up here on the top floor. The thought makes me even harder.
My cock is rubbing up against your ass cheeks, only the thin fabric of your skirt separating them. I lift your skirt so I can see your beautiful ass. My hips grab your ass and bring you toward me so that my cock is nestled between your cheeks. The pleasure of that makes me weak at the knees.
I pull back and grab my cock with one hand and push your back down slightly with the other so that your ass and pussy open up. I position my cock at the entrance of your pussy and push in slightly. You're still wet from the oral sex and my cock feels like it has entered paradise.
With my hands on your hips, I pull you slowly back into me, your pussy enveloping my cock until I'm completely up against your ass. I pull out almost all the way and then start to fuck you slowly. The sight of you in front of me with your hands on the window as I fuck you from behind may be the sexiest thing I've ever seen in my life. My hands move up your back as I continue to fuck you. I run my fingers through your hair, grabbing a handful and pulling your head back. As I continue to fuck you, my passion begins to take over and I can't help myself from speeding up. Your moans, which you try to stifle, given that we are still in my office, are a further turn on and let me know that you're getting close.
I grab your shoulders, pulling you into my cock with each thrust. My cock is swollen from the feeling of your pussy, the sight of your body, and the sheer insanity of the situation. I can't believe I'm fucking one of my students in my office, during the day, with my colleagues just outside the door.
I grab the back of your neck with my left hand and lick the fingers of my right. I can feel both of us getting closer. I reach around with my right hand under your skirt and find your clitoris. My wet fingers work your clit as I fuck you harder and faster from behind. Your stifled moans become faster and more ragged and louder.
As I approach my climax, my arms reach under yours and grab your shoulders so that I can increase the pace and force of my thrusts even more. As you reach your orgasm, my balls contract and my cum shoots into you. I shoot wave after wave into you, feeling that I've never experienced so powerful an orgasm. Spent, but with my cock still inside you, we collapse onto my chair, you sitting on my cock and lap. You turn your head to me and smile.
"What's next?"